Theravāda Vinayapiṭaka
Monks’ rules and their analysis
Monks’ Training (Sekhiya) 43
… in Anāthapiṇḍika’s monastery. Now at that time the group of six monks talked with a mouthful in the mouth … “…
‘I will not talk with a mouthful in the mouth,’ is a training to be observed.”
One should not talk with a mouthful in the mouth. Whoever out of disrespect talks with a mouthful in the mouth, there is an offence of wrong-doing.
There is no offence if it is unintentional … if he is the first wrong-doer.