四分律比丘含注戒本 2.491

2.491

The Buddha was in the country of Ceti. Sāgata, acting as the Buddha's attendant, went to the dragon chamber of a matted-hair brāhmaṇa to lodge, and subdued the dragon during the night. The next morning he showed it to the king of Kauśāmbī. Later, when wandering through that country, he was given black liquor and lay drunk on the road. After the Buddha spoke of the ten faults, he formulated the precept.