user24100: First text screenshot says MLD. 131. Where is that from?

Second text screenshot says M. 19. Where is that from?

Screenshots are taken from Ven. Dhammajivas book called Mahasi Insight Meditation.

user24126: The First one is from: BhaddekaRatta Sutta
The Second one is from: Maha Parinibbana Sutta
I have given you the links But you cannot find the Pali text in English.  I converted into sinhala and search with sinhala words and find the related English text for you.
Those two sutta's are little bit longer one's but worthwhile reading the whole context rather than the specific place to get the full idea. Also these links may helpful for you to understand many Buddhist text in English because it has Thripitaka converted to english.
May Triple Gem bless you.

24100: <p>First text screenshot says <strong>MLD. 131</strong>. Where is that from?
<a href="https://i.stack.imgur.com/NfXGL.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/NfXGL.png" alt="enter image description here" /></a></p>
<p>Second text screenshot says <strong>M. 19</strong>. Where is that from?
<a href="https://i.stack.imgur.com/DUtE9.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/DUtE9.png" alt="enter image description here" /></a></p>
<p>Screenshots are taken from Ven. Dhammajivas book called <a href="https://www.vipassana.com/resources/box/MahasiInsightMeditation-v20-vf.pdf" rel="nofollow noreferrer"><em>Mahasi Insight Meditation</em></a>.</p>
 24126: <p>The First one is from: <a href="https://www.accesstoinsight.org/tipitaka/mn/mn.131.than.html" rel="nofollow noreferrer">BhaddekaRatta Sutta</a>
The Second one is from: <a href="https://www.accesstoinsight.org/tipitaka/dn/dn.16.1-6.vaji.html" rel="nofollow noreferrer">Maha Parinibbana Sutta</a></p>
<p>I have given you the links But you cannot find the Pali text in English.  I converted into sinhala and search with sinhala words and find the related English text for you.
Those two sutta's are little bit longer one's but worthwhile reading the whole context rather than the specific place to get the full idea. Also these links may helpful for you to understand many Buddhist text in English because it has Thripitaka converted to english.
May Triple Gem bless you.</p>
