user-1: I remember this phrase but I have not been able to locate it in the texts.
I do not recall the correct words but it's something like this: "Meditate/practice as if your hair is/were on fire".
I have searched on Buddhism SE and on Google and found the phrase mentioned a couple of times but no solution to the origin of it. This article mentioned by Matthew says;

"Practice like your hair is on fire!
A traditional aphorism, which probably goes back to Buddhism in India. Gelek Rinpoche makes it the theme of his recent article in Buddhadharma. And it shows up in the Zen tradition and elsewhere."

And this article says:

Zazen makes waiting into a science. I'm intrigued by the Zen injunction "Sit as if your hair were on fire."

Still no solution to the origin of the phrase. I'm looking for valid sources such as the Theravadan, East Asian and Tibetan texts.
Thank you for your time.

user-1: Samvega is the very root of practice.

Affirming the Truths of the Heart: The Buddhist Teachings on Samvega
  & Pasada, by Thanissaro Bhikkhu (1997; 5pp./14KB)
      Popular interpretations of Buddhism today often ignore the importance of two powerful emotions, emotions that propelled the
  Buddha — and all those who have sought Awakening since — towards the
  goal of Awakening: samvega, a sense of urgency to escape the round of
  meaningless existence; and pasada, a clarity and serene confidence
  that allows one to proceed confidently towards the goal without
  lapsing into despair. In this short essay the author explores the
  meaning of these essential emotions and how we can encourage them to
  blossom in our lives.

Verbal mentions are very often, since an idea of Dukkha, and the urgency to escape, are the righteous reasons to practice the Eightfold Path:
Person with Turban or head on fire: AN 6.20 (a, b), AN 10.51, AN 10.54, Thag 1.39 (already generous mentioned by Upasaka Dharmasena here) and point out a very prerequiste to practice: aroused persistence:
(Note: this answer has not been given with the agreement to be means of trade or the purpose of trade and keep people trapped and bound. How you handle it lies in your sphere, but does not excuse the deed here either.)

user10691: 
The Blessed One:
“Short is the life span of human beings, The good man should disdain
it. One should live like one with head aflame: There is no avoiding
Death’s arrival.”

Source : SN 4.9 Paṭhamaāyusutta https://suttacentral.net/sn4.9/en/bodhi

user20385: Its referred to in the Phena Sutta (or Phena Pinduma Sutta) as follows, translated by Thanissaro Bhikkhu:

Thus a monk, persistence aroused,
should view the aggregates
by day & by night,
mindful, alert;
should discard all fetters;
should make himself
his own refuge;
should live as if
his head were on fire —
in hopes of the state
with no falling away.

Alternative translation here by Bhikkhu Sujato:

An energetic mendicant
should examine the aggregates like this,
with situational awareness and mindfulness
whether by day or by night.
They should give up all fetters,
and make a refuge for themselves.
They should live as though their head was on fire,
aspiring to the imperishable state.”


user11467: Dear Lanka:  In response to your request for a reference to "Hair on fire", Bhikkhu Bodhi ed  Anguttara Nikaya:  Book of Fours II93 verse 3 pg, 474  "...Just as one whose clothes or head had caught fire would put forth extraordinary desire, effort, zeal, enthusiasm, indefatigability, mindfulness, and clear comprehension to extinguish {the fire on} his clothes or head, so that person should put forth extraordinary desire, effort, zeal, enthusiasm, indefatigability, mindfulness, and clear comprehension to obtain both those wholesome qualities. Then, some time later, he gains both internal serenity of mind and the higher wisdom or insight into phenomena. "  The reference varies slightly in repetitions found on pgs, 879, 1222, 1405 & 1498  Hope this may be of some help to you. /jojo

user295: 
Tissa (Thag 1.39)   {Thag 39}
As if struck by a sword,
  as if his head were on fire,
  a monk should live the wandering life
      — mindful —
  for the abandoning of sensual passion.

Source: http://www.accesstoinsight.org/tipitaka/kn/thag/thag.01.00x.than.html#passage-39

-1: <p>I remember this phrase but I have not been able to locate it in the texts.</p>
<p>I do not recall the correct words but it's something like this: <em>&quot;Meditate/practice as if your hair is/were on fire&quot;</em>.</p>
<p>I have searched on Buddhism SE and on Google and found the phrase mentioned a couple of times but no solution to the origin of it. <a href="http://musingsbyken.blogspot.dk/2009/03/is-your-hair-on-fire.html" rel="nofollow noreferrer">This article</a> mentioned by <a href="https://buddhism.stackexchange.com/questions/6009/can-you-meditate-too-much-as-part-of-a-daily-routine/6011#6011">Matthew</a> says;</p>
<blockquote>
<p>&quot;Practice like your hair is on fire!</p>
<p>A traditional aphorism, which probably goes back to Buddhism in India. Gelek Rinpoche makes it the theme of his recent article in Buddhadharma. And it shows up in the Zen tradition and elsewhere.&quot;</p>
</blockquote>
<p>And <a href="http://omlc.org/aikido/talk/phillips/zazen.html" rel="nofollow noreferrer">this article</a> says:</p>
<blockquote>
<p>Zazen makes waiting into a science. I'm intrigued by the Zen injunction &quot;Sit as if your hair were on fire.&quot;</p>
</blockquote>
<p>Still no solution to the origin of the phrase. I'm looking for valid sources such as the <em>Theravadan, East Asian and Tibetan texts</em>.</p>
<p>Thank you for your time.</p>
 -1: <p>Samvega is the very root of practice.</p>

<blockquote>
  <p><a href="http://zugangzureinsicht.org/html/lib/authors/thanissaro/affirming_en.html" rel="nofollow">Affirming the Truths of the Heart: The Buddhist Teachings on Samvega
  &amp; Pasada</a>, by Thanissaro Bhikkhu (1997; 5pp./14KB)
      Popular interpretations of Buddhism today often ignore the importance of two powerful emotions, emotions that propelled the
  Buddha — and all those who have sought Awakening since — towards the
  goal of Awakening: samvega, a sense of urgency to escape the round of
  meaningless existence; and pasada, a clarity and serene confidence
  that allows one to proceed confidently towards the goal without
  lapsing into despair. In this short essay the author explores the
  meaning of these essential emotions and how we can encourage them to
  blossom in our lives.</p>
</blockquote>

<p>Verbal mentions are very often, since an idea of Dukkha, and the urgency to escape, are the righteous reasons to practice the Eightfold Path:
Person with Turban or head on fire: AN 6.20 (<a href="http://zugangzureinsicht.org/html/tipitaka/an/an06/an06.020.than_en.html#turban1" rel="nofollow">a</a>, <a href="http://zugangzureinsicht.org/html/tipitaka/an/an06/an06.020.than_en.html#turban2" rel="nofollow">b</a>), <a href="http://zugangzureinsicht.org/html/tipitaka/an/an10/an10.051.than_en.html#turban" rel="nofollow">AN 10.51</a>, <a href="http://zugangzureinsicht.org/html/tipitaka/an/an10/an10.054.than_en.html#turban" rel="nofollow">AN 10.54</a>, <a href="http://zugangzureinsicht.org/html/tipitaka/kn/thag/thag.01.00x.than_en.html#passage-39" rel="nofollow">Thag 1.39</a> (already generous mentioned by Upasaka Dharmasena here) and point out a very prerequiste to practice: <strong><a href="http://zugangzureinsicht.org/html/lib/study/conversation_en.html#persistence" rel="nofollow">aroused persistence</a></strong>:</p>

<p><em>(Note: this answer has not been given with the agreement to be means of trade or the purpose of trade and keep people trapped and bound. How you handle it lies in your sphere, but does not excuse the deed here either.)</em></p>
 10691: <blockquote>
<p>The Blessed One:</p>
<p>“Short is the life span of human beings, The good man should disdain
it. One should live like one with head aflame: There is no avoiding
Death’s arrival.”</p>
</blockquote>
<p>Source : SN 4.9 Paṭhamaāyusutta <a href="https://suttacentral.net/sn4.9/en/bodhi" rel="nofollow noreferrer">https://suttacentral.net/sn4.9/en/bodhi</a></p>
 20385: <p>Its referred to in the <a href="https://www.accesstoinsight.org/tipitaka/sn/sn22/sn22.095.than.html" rel="nofollow noreferrer">Phena Sutta</a> (or Phena Pinduma Sutta) as follows, translated by Thanissaro Bhikkhu:</p>
<blockquote>
<p>Thus a monk, persistence aroused,<br />
should view the aggregates<br />
by day &amp; by night,<br />
mindful, alert;<br />
should discard all fetters;<br />
should make himself<br />
his own refuge;<br />
should live <strong>as if<br />
his head were on fire</strong> —<br />
in hopes of the state<br />
with no falling away.</p>
</blockquote>
<p>Alternative translation <a href="https://suttacentral.net/sn22.95/en/sujato" rel="nofollow noreferrer">here</a> by Bhikkhu Sujato:</p>
<blockquote>
<p>An energetic mendicant<br />
should examine the aggregates like this,<br />
with situational awareness and mindfulness<br />
whether by day or by night.</p>
<p>They should give up all fetters,<br />
and make a refuge for themselves.<br />
They should live <strong>as though their head was on fire</strong>,<br />
aspiring to the imperishable state.”</p>
</blockquote>
 11467: <p>Dear Lanka:  In response to your request for a reference to "Hair on fire", Bhikkhu Bodhi ed  Anguttara Nikaya:  Book of Fours II93 verse 3 pg, 474  "...Just as one whose clothes or head had caught fire would put forth extraordinary desire, effort, zeal, enthusiasm, indefatigability, mindfulness, and clear comprehension to extinguish {the fire on} his clothes or head, so that person should put forth extraordinary desire, effort, zeal, enthusiasm, indefatigability, mindfulness, and clear comprehension to obtain both those wholesome qualities. Then, some time later, he gains both internal serenity of mind and the higher wisdom or insight into phenomena. "  The reference varies slightly in repetitions found on pgs, 879, 1222, 1405 &amp; 1498  Hope this may be of some help to you. /jojo</p>
 295: <blockquote>
  <p>Tissa (Thag 1.39)   {Thag 39}</p>
  
  <p>As if struck by a sword,
  as if his head were on fire,
  a monk should live the wandering life
      — mindful —
  for the abandoning of sensual passion.</p>
</blockquote>

<p>Source: <a href="http://www.accesstoinsight.org/tipitaka/kn/thag/thag.01.00x.than.html#passage-39">http://www.accesstoinsight.org/tipitaka/kn/thag/thag.01.00x.than.html#passage-39</a></p>
