Theravāda Vinayapiṭaka
Monks’ rules and their analysis
Monks’ Training (Sekhiya) 48
… in Anāthapiṇḍika’s monastery. Now at that time the group of six monks ate scattering lumps of boiled rice … “…
‘I will not eat scattering lumps of boiled rice,’ is a training to be observed.”
One should not eat scattering lumps of boiled rice. Whoever out of disrespect eats scattering lumps of boiled rice, there is an offence of wrong-doing.
There is no offence if it is unintentional, if he is not thinking, if he does not know, if he is ill, if, getting rid of the crumbs, a lump of boiled rice is got rid of, if there are accidents, if he is mad, if he is the first wrongdoer.