From:
Theravāda Vinaya Theravāda Collection on Monastic Law
Mahāvibhaṅga The Great Analysis
Sekhiyakaṇḍa The chapter on training
Surusuruvagga The subchapter on slurping
52. Hatthanillehakasikkhāpada 52. The training rule on licking the hands
Tena samayena buddho bhagavā sāvatthiyaṁ viharati jetavane anāthapiṇḍikassa ārāme. At one time the Buddha was staying at Sāvatthī in the Jeta Grove, Anāthapiṇḍika’s Monastery.
Tena kho pana samayena chabbaggiyā bhikkhū hatthanillehakaṁ bhuñjanti …pe…. At that time the monks from the group of six were licking their hands while eating. …
“Na hatthanillehakaṁ bhuñjissāmīti sikkhā karaṇīyā”ti. “‘I will not lick my hands while eating,’ this is how you should train.”
Na hatthanillehakaṁ bhuñjitabbaṁ. One should not lick one’s hands while eating.
Yo anādariyaṁ paṭicca hatthanillehakaṁ bhuñjati, āpatti dukkaṭassa. If a monk, out of disrespect, licks his hands while eating, he commits an offense of wrong conduct.
Anāpatti—There is no offense:
asañcicca …pe… if it is unintentional;
ādikammikassāti. if he is the first offender.
Dutiyasikkhāpadaṁ niṭṭhitaṁ. The second training rule is finished.