user18: In this answer, I mention that the Bodhisatta had trouble keeping down coarse alms food, to the extent that he felt like his stomach was going to leap out of his throat. @ThiagoSilva asked in a comment where the story is found, and I can't quite remember. Does anyone have a reference handy?
EDIT: Here's an example of how the passage is described, though no mention of where it comes from:

Having enjoyed the kingly bliss which was as great as that of a Universal Monarch only a matter of days ago, he made an effort to eat a morsel of food which was a mixture of coarse and fine edible things in assorted colours. As he was about to put the morsel into his mouth he felt miserable and almost vomited with the intestines turning upside down, for he had never seen such kind of food in his life and found it particularly disgusting. Then he admonished himself by saying; "You Siddhattha, in spite of the fact that you have been reigning supreme in a palace where food and drinks are available at your pleasure and where you have meals of three-year-old seasoned fragrant rice with different delicacies whenever you like, you, on seeing a recluse in robe of rags contemplated, "When shall I eat the meals obtained by going on alms round from house to house after becoming a recluse like him? When will the time come for me to live on meals thus collected? And have you not renounced the world and become a recluse with such thoughts? Now that your dream has come true, why do you like to change your mind?" Then without the slightest revulsion he took the meal that was so rough.
(source)


user111: It is from the The Great Chronicles of the Buddhas by venerable Mingun Sayadaw.
Chapter 4, page 280, paragraph 3. It is preceded by the following.
The Bodhishtta's Visit to Rajagaha City
After becoming a recluse, the Bodhisatta, after spending seven full days in ascetic bliss in the nearby mango grove called Anupiya, travelled a journey of thirty yojanas on foot in one single day and entered the city of Rajagaha. (This is the statement made in the Buddhavamsa Commentary and the Jataka Commentary.)
(According to the Sutta Nipata Commentary, however,) the Bodhisatta, after becoming a recluse, observed the Ajivattamaka sila, the Precepts with pure livelihood as the eighth, and journeyed to Rajagaha, thirty yojanas away from the banks of Anoma in seven days.

user715: The quote appears in this text. However it appears to be a Victorian-era translation of the Jâtaka without much details about the version of the original from which it was translated.

BUDDHISM
IN TRANSLATIONS
Passages Selected from the Buddhist Sacred Books
and Translated from the Original Pâli into English by
Henry Clarke Warren
Published by Harvard University Press {1896}

http://www.sacred-texts.com/bud/bits/bits007.htm

§ 7. THE GREAT STRUGGLE. Translated from the Introduction to the
  Jâtaka (i.6529).
NOW the Future Buddha, having thus retired from the world,--in that
  place there was a mango-grove named Anupiya, and here he first spent a
  week in the joy of having retired from the world,--in one day went on
  foot to Râjagaha, a distance of thirty leagues, and entering the city,
  he begged for food from house to house without passing any by. By the
  beauty of the Future Buddha, the whole city was thrown into a
  commotion, like that into which Râjagaha was thrown by the entrance of
  Dhanapâlaka, or like that into which the
p. 68 [J.i.664 heavenly city was thrown by the entrance of the chief
  of the Titans.
Then ran the king's men to the palace, and made announcement,--
"Sire, there is a being of such and such appearance going about the
  city begging for food. Whether he be a god, or a man, or a serpent, or
  a bird, we do not know."
Then the king, standing on the roof of his palace, and thence
  beholding the Great Being, became amazed and astonished, and commanded
  his men,--
"Look ye now! Go and investigate this! If this person be not a man,
  he will vanish from sight as soon as he leaves the city; if, namely,
  he be a god, he will depart by way of the air; if a serpent, he will
  sink into the ground. But if he be a human being, he will eat the food
  he has obtained in alms."
Now the Great Being, after collecting a number of scraps,
  sufficient, as he judged, for his sustenance, left the city by the
  same gate he had entered, and sitting down with his face to the east,
  in the shade of Pandava rock, he attempted to eat his meal. But his
  stomach turned, and he felt as if his inwards were on the point of
  coming out by his mouth. Thereupon, in the midst of his distress at
  that repulsive food, --for in that existence he had never before so
  much as seen such fare,--he began to admonish himself, saying,
  "Siddhattha, although you were born into a family having plenty to eat
  and drink, into a station in life where you lived on fragrant third
  season's rice1 with various sauces of the finest flavors, yet when you
  saw a monk clad in garments taken from the rubbish heap, you
  exclaimed, 'Oh, when shall I be like him, and eat food which I have
  begged? Will that time ever come?' And then you retired from the
  world. And
p. 69 [J.i.6622 now that you have your wish, and have renounced all,
  what, pray, is this you are doing?" When he had thus admonished
  himself, his disgust subsided, and he ate his meal.


user18: I found it in the introduction to the Jatakas, which seems to be the original source:

Now the Great Being, after collecting a number of scraps, sufficient, as he judged, for his sustenance, left the city by the same gate he had entered, and sitting down with his face to the east, in the shade of Pandava rock, he attempted to eat his meal. But his stomach turned, and he felt as if his inwards were on the point of coming out by his mouth. Thereupon, in the midst of his distress at that repulsive food, --for in that existence he had never before so much as seen such fare,--he began to admonish himself, saying, "Siddhattha, although you were born into a family having plenty to eat and drink, into a station in life where you lived on fragrant third season's rice1 with various sauces of the finest flavors, yet when you saw a monk clad in garments taken from the rubbish heap, you exclaimed, 'Oh, when shall I be like him, and eat food which I have begged? Will that time ever come?' And then you retired from the world. And now that you have your wish, and have renounced all, what, pray, is this you are doing?" When he had thus admonished himself, his disgust subsided, and he ate his meal.
-- Jāt-A nidānakathā (from Buddhism In Translations, Henry Clarke Warren, trans.)

The relevant Pali is "antāni parivattitvā mukhena nikkhamanākārappattāni viya ahesuṃ" - It was like the intestines, having churned, attained the state of leaving through the mouth."
The Buddhavamsa doesn't mention this reflection, saying of his first alms round simply:

nisīditvā āhāraṃ paccavekkhitvā nibbikāro paribhuñji
Having sat down, having reflected on the food, unperturbed, he ate.
-- Bv-A, nidānakathā


18: <p>In <a href="https://buddhism.stackexchange.com/a/10116/18">this answer</a>, I mention that the Bodhisatta had trouble keeping down coarse alms food, to the extent that he felt like his stomach was going to leap out of his throat. @ThiagoSilva asked in a comment where the story is found, and I can't quite remember. Does anyone have a reference handy?</p>
<p>EDIT: Here's an example of how the passage is described, though no mention of where it comes from:</p>
<blockquote>
<p>Having enjoyed the kingly bliss which was as great as that of a Universal Monarch only a matter of days ago, he made an effort to eat a morsel of food which was a mixture of coarse and fine edible things in assorted colours. As he was about to put the morsel into his mouth he felt miserable and almost vomited with the intestines turning upside down, for he had never seen such kind of food in his life and found it particularly disgusting. Then he admonished himself by saying; &quot;You Siddhattha, in spite of the fact that you have been reigning supreme in a palace where food and drinks are available at your pleasure and where you have meals of three-year-old seasoned fragrant rice with different delicacies whenever you like, you, on seeing a recluse in robe of rags contemplated, &quot;When shall I eat the meals obtained by going on alms round from house to house after becoming a recluse like him? When will the time come for me to live on meals thus collected? And have you not renounced the world and become a recluse with such thoughts? Now that your dream has come true, why do you like to change your mind?&quot; Then without the slightest revulsion he took the meal that was so rough.</p>
<p>(<a href="http://realtruthlife.blogspot.ca/2011/08/maha-buddhavamsa-bodhisattas-visit-to.html#.VaPNy5NuB5E" rel="noreferrer">source</a>)</p>
</blockquote>
 111: <p>It is from the <a href="http://www.bps.lk/olib/mi/mi014.pdf" rel="nofollow">The Great Chronicles of the Buddhas</a> by venerable Mingun Sayadaw.</p>

<p>Chapter 4, page 280, paragraph 3. It is preceded by the following.</p>

<p><strong>The Bodhishtta's Visit to Rajagaha City</strong></p>

<p>After becoming a recluse, the Bodhisatta, after spending seven full days in ascetic bliss in the nearby mango grove called Anupiya, travelled a journey of thirty yojanas on foot in one single day and entered the city of Rajagaha. (This is the statement made in the <strong>Buddhavamsa Commentary</strong> and the <strong>Jataka Commentary</strong>.)
(According to the <strong>Sutta Nipata Commentary</strong>, however,) the Bodhisatta, after becoming a recluse, observed the Ajivattamaka sila, the Precepts with pure livelihood as the eighth, and journeyed to Rajagaha, thirty yojanas away from the banks of Anoma in seven days.</p>
 715: <p>The quote appears in this text. However it appears to be a Victorian-era translation of the Jâtaka without much details about the version of the original from which it was translated.</p>

<blockquote>
  <p>BUDDHISM</p>
  
  <p>IN TRANSLATIONS</p>
  
  <p>Passages Selected from the Buddhist Sacred Books</p>
  
  <p>and Translated from the Original Pâli into English by</p>
  
  <p>Henry Clarke Warren</p>
  
  <p>Published by Harvard University Press {1896}</p>
</blockquote>

<p><a href="http://www.sacred-texts.com/bud/bits/bits007.htm">http://www.sacred-texts.com/bud/bits/bits007.htm</a></p>

<blockquote>
  <p>§ 7. THE GREAT STRUGGLE. Translated from the Introduction to the
  Jâtaka (i.6529).</p>
  
  <p>NOW the Future Buddha, having thus retired from the world,--in that
  place there was a mango-grove named Anupiya, and here he first spent a
  week in the joy of having retired from the world,--in one day went on
  foot to Râjagaha, a distance of thirty leagues, and entering the city,
  he begged for food from house to house without passing any by. By the
  beauty of the Future Buddha, the whole city was thrown into a
  commotion, like that into which Râjagaha was thrown by the entrance of
  Dhanapâlaka, or like that into which the</p>
  
  <p>p. 68 [J.i.664 heavenly city was thrown by the entrance of the chief
  of the Titans.</p>
  
  <p>Then ran the king's men to the palace, and made announcement,--</p>
  
  <p>"Sire, there is a being of such and such appearance going about the
  city begging for food. Whether he be a god, or a man, or a serpent, or
  a bird, we do not know."</p>
  
  <p>Then the king, standing on the roof of his palace, and thence
  beholding the Great Being, became amazed and astonished, and commanded
  his men,--</p>
  
  <p>"Look ye now! Go and investigate this! If this person be not a man,
  he will vanish from sight as soon as he leaves the city; if, namely,
  he be a god, he will depart by way of the air; if a serpent, he will
  sink into the ground. But if he be a human being, he will eat the food
  he has obtained in alms."</p>
  
  <p>Now the Great Being, after collecting a number of scraps,
  sufficient, as he judged, for his sustenance, left the city by the
  same gate he had entered, and sitting down with his face to the east,
  in the shade of Pandava rock, he attempted to eat his meal. But his
  stomach turned, and he felt as if his inwards were on the point of
  coming out by his mouth. Thereupon, in the midst of his distress at
  that repulsive food, --for in that existence he had never before so
  much as seen such fare,--he began to admonish himself, saying,
  "Siddhattha, although you were born into a family having plenty to eat
  and drink, into a station in life where you lived on fragrant third
  season's rice1 with various sauces of the finest flavors, yet when you
  saw a monk clad in garments taken from the rubbish heap, you
  exclaimed, 'Oh, when shall I be like him, and eat food which I have
  begged? Will that time ever come?' And then you retired from the
  world. And</p>
  
  <p>p. 69 [J.i.6622 now that you have your wish, and have renounced all,
  what, pray, is this you are doing?" When he had thus admonished
  himself, his disgust subsided, and he ate his meal.</p>
</blockquote>
 18: <p>I found it in the introduction to the Jatakas, which seems to be the original source:</p>
<blockquote>
<p>Now the Great Being, after collecting a number of scraps, sufficient, as he judged, for his sustenance, left the city by the same gate he had entered, and sitting down with his face to the east, in the shade of Pandava rock, he attempted to eat his meal. But his stomach turned, and he felt as if his inwards were on the point of coming out by his mouth. Thereupon, in the midst of his distress at that repulsive food, --for in that existence he had never before so much as seen such fare,--he began to admonish himself, saying, &quot;Siddhattha, although you were born into a family having plenty to eat and drink, into a station in life where you lived on fragrant third season's rice1 with various sauces of the finest flavors, yet when you saw a monk clad in garments taken from the rubbish heap, you exclaimed, 'Oh, when shall I be like him, and eat food which I have begged? Will that time ever come?' And then you retired from the world. And now that you have your wish, and have renounced all, what, pray, is this you are doing?&quot; When he had thus admonished himself, his disgust subsided, and he ate his meal.</p>
<p><em>-- Jāt-A nidānakathā (<a href="http://www.sacred-texts.com/bud/bits/bits007.htm" rel="nofollow noreferrer">from Buddhism In Translations, Henry Clarke Warren, trans.</a>)</em></p>
</blockquote>
<p>The relevant Pali is &quot;<em>antāni parivattitvā mukhena nikkhamanākārappattāni viya ahesuṃ</em>&quot; - It was like the intestines, having churned, attained the state of leaving through the mouth.&quot;</p>
<p>The Buddhavamsa doesn't mention this reflection, saying of his first alms round simply:</p>
<blockquote>
<p><em>nisīditvā āhāraṃ paccavekkhitvā nibbikāro paribhuñji</em></p>
<p>Having sat down, having reflected on the food, unperturbed, he ate.</p>
<p>-- <em>Bv-A, nidānakathā</em></p>
</blockquote>
