1"Bhikkhus, if one's clothes or head were ablaze, what should be done about it?"

"Venerable sir, if one's clothes or head were ablaze, to extinguish one's blazing clothes or head one should arouse extraordinary desire, make an extraordinary effort, stir up zeal and enthusiasm, be unremitting, and exercise mindfulness and clear comprehension."[n.395] Many of these expressions are also at 12:84–93.

2"Bhikkhus, one might look on equanimously at one's blazing clothes or head, paying no attention to them, but so long as one has not made the breakthrough to the Four Noble Truths as they really are, in order to make the breakthrough one should arouse extraordinary desire, make an extraordinary effort, stir up zeal and enthusiasm, be unremitting, and exercise mindfulness and clear comprehension.

What four?
The noble truth of suffering,
the noble truth of the origin of suffering,
the noble truth of the cessation of suffering,
the noble truth of the way leading to the cessation of suffering.

3"Therefore, bhikkhus, an exertion should be made to understand: ‘This is suffering.’[n.376] Tasmātiha bhikkhave idaṁ dukkhan ti yogo karaṇīyo. Spk: Since a concentrated bhikkhu understands the Four Noble Truths as they really are, therefore you should make an exertion to become concentrated in order to understand the four truths as they really are. And since the round of existence increases for those who do not penetrate them, but stops increasing from the time they are penetrated, therefore you should make an exertion to understand them, thinking, "Let the round not increase for us."
An exertion should be made to understand: ‘This is the origin of suffering.’
An exertion should be made to understand: ‘This is the cessation of suffering.’
An exertion should be made to understand: ‘This is the way leading to the cessation of suffering.’"

1"Āditte, bhikkhave, cele vā sīse vā kimassa karaṇīyan"ti?

"Āditte, bhante, cele vā sīse vā, tasseva celassa vā sīsassa vā nibbāpanāya adhimatto chando ca vāyāmo ca ussāho ca ussoḷhī ca appaṭivānī ca sati ca sampajaññañca karaṇīyan"ti.

2"Ādittaṁ, bhikkhave, celaṁ vā sīsaṁ vā ajjhupekkhitvā amanasikaritvā anabhisametānaṁ catunnaṁ ariyasaccānaṁ yathābhūtaṁ abhisamayāya adhimatto chando ca vāyāmo ca ussāho ca ussoḷhī ca appaṭivānī ca sati ca sampajaññañca karaṇīyaṁ.

Katamesaṁ catunnaṁ? Dukkhassa ariyasaccassa … pe … dukkhanirodhagāminiyā paṭipadāya ariyasaccassa.

3Tasmātiha, bhikkhave, ‘idaṁ dukkhan’ti yogo karaṇīyo … pe … ‘Ayaṁ dukkhanirodhagāminī paṭipadā’ti yogo karaṇīyo"ti.

Catutthaṁ.