From:
Theravāda Vinaya Theravāda Collection on Monastic Law
Mahāvibhaṅga The Great Analysis
Sekhiyakaṇḍa The chapter on training
Sakkaccavagga The subchapter on respectfully
31. Sakkaccasikkhāpada 31. The training rule on respectfully
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 asakkaccaṁ piṇḍapātaṁ bhuñjanti abhuñjitukāmā viya …pe…. At that time the monks from the group of six were eating almsfood contemptuously, as if not wanting to eat it. …
“Sakkaccaṁ piṇḍapātaṁ bhuñjissāmīti sikkhā karaṇīyā”ti. “‘I will eat almsfood respectfully,’ this is how you should train.”
Sakkaccaṁ piṇḍapāto bhuñjitabbo. Almsfood is to be eaten respectfully.
Yo anādariyaṁ paṭicca asakkaccaṁ piṇḍapātaṁ bhuñjati, āpatti dukkaṭassa. If a monk, out of disrespect, eats almsfood contemptuously, he commits an offense of wrong conduct.
Anāpatti—There is no offense:
asañcicca, if it is unintentional;
assatiyā, if he is not mindful;
ajānantassa, if he does not know;
gilānassa, if he is sick;
āpadāsu, if there is an emergency;
ummattakassa, if he is insane;
ādikammikassāti. if he is the first offender.
Paṭhamasikkhāpadaṁ niṭṭhitaṁ. The first training rule is finished.