釋氏要覽 1.443

1.443

今時云掇齋也。鼻奈耶云。佛遊王舍城。諸長者或請一二比丘齋。其不請自往者有四五。諸長者譏嫌（以食不足故也）佛制戒云。不請強往者。犯波逸提。

Nowadays this is called duozhai 掇齋 [crashing a meal]. The Vinaya says: "The Buddha was traveling in Rājagṛha. Various elders would invite one or two monks to a meal, but four or five who were uninvited went on their own. The elders criticized and disliked this (because the food was insufficient). The Buddha formulated a precept, saying: 'Whoever forces themselves [upon a meal] without an invitation commits a pāyattika.'"