四分律比丘含注戒本 2.249

2.249

佛在舍衛。六群比丘與六群尼同乘船上水下水，居士共嫌。比丘舉過白佛，因制此戒。

The Buddha was in Śrāvastī. The group of six bhikṣus and the group of six bhikṣuṇīs boarded a boat together, traveling upriver and downriver. Householders censured them. The bhikṣus brought up this fault and reported it to the Buddha, who instituted this rule on account of it.