四分律比丘含注戒本 2.19

2.19

佛在舍衛。六群傳他彼此語，令眾鬪諍，不能除滅。比丘以過白佛。便引「野干鬪亂二獸，況復於人」，便訶責已，而制此戒。

The Buddha was in Śrāvastī. The group of six [bhikṣus] carried talk back and forth between others, causing the assembly to quarrel and dispute without being able to quell it. Bhikṣus reported the fault to the Buddha. He cited [the parable of] "the jackal sowing discord between two beasts, let alone among human beings," and having rebuked them, formulated this precept.