Theravāda Vinayapiṭaka
Monks’ rules and their analysis
Monks’ Training (Sekhiya) 53
… in Anāthapiṇḍika’s monastery. Now at that time the group of six monks ate licking the bowl … “…
‘I will not eat licking the bowl,’ is a training to be observed.”
One should not eat licking the bowl …
There is no offence if it is unintentional … if he is ill, if from an insignificant remainder he eats having collected, having licked at one side, if there are accidents, if he is mad, if he is the first wrong-doer.