Theravāda Vinayapiṭaka
Monks’ rules and their analysis
Monks’ Training (Sekhiya) 28
… in Anāthapiṇḍika’s monastery. Now at that time the group of six monks accepted almsfood looking about here and there; they did not know that they were piled up and overflowing … “…
‘Thinking of the bowl will I accept almsfood,’ is a training to be observed.”
One should accept almsfood thinking of the bowl. Whoever out of disrespect accepts almsfood, looking about here and there, there is an offence of wrong-doing.
There is no offence if it is unintentional … if he is the first wrong-doer.