四分律比丘戒本 1.118

1.118

"If a bhikṣu, having previously accepted an invitation, goes to visit other households before or after the meal without informing other bhikṣus, except on a suitable occasion, it is a pāyattika. A suitable occasion means: a time of illness, a time of making robes, or a time of offering robes; this is called a suitable occasion.