四分律比丘含注戒本 2.205

2.205

The Buddha was in Śrāvastī. When the bhikṣuṇīs heard that the instructing master was coming, they went out to welcome and serve him. The group of six became jealous and said: “He has no sincerity; he instructs the bhikṣuṇīs merely for food.” The bhikṣus reported this fault to the Buddha, who instituted the rule on account of it.