大方廣佛華嚴經隨疏演義鈔 19.55

19.55

疏「而龍受三歸」者，《菩薩處胎經》，佛自說昔為金翅鳥七寶宮殿等，時乃入海求龍為食。時彼海中有化生龍龍子，八日十四日十五日受如來齋八禁戒法。時鳥銜得龍出海，金翅鳥法，若食龍時先從尾吞。求尾不得，已經日夜。明日龍出尾示金翅鳥云：「化生龍者，我身是也。我若不持八關齋法者，汝可食我。我奉戒，汝屈滅我。」故金翅聞已，悔過自責云：「佛之威神甚深難量。」請龍入宮，龍即隨入，乃請龍受八戒。

Regarding the Commentary's words, "And dragons receive the three refuges": in the Bodhisattvagocarodbhava-sūtra, the Buddha himself related that in the past, when he was a gold-winged bird with seven-jeweled palaces and so forth, he then entered the sea to seek dragons for food. At that time, in that sea, there was a transformationally born dragon son who on the eighth, fourteenth, and fifteenth days undertook the Tathāgata's fast and the eight prohibitive precepts. At that time, the bird held the dragon in its beak and emerged from the sea. By the rule of the gold-winged bird, when eating a dragon it always swallows it tail first. Seeking its tail, it could not find it, and a day and night passed. The next day, the dragon stuck out its tail, showed it to the gold-winged bird, and said: 'I am a transformationally born dragon. If I were not upholding the eightfold fasting precepts, you might eat me; but I observe the precepts, and you are unjustly destroying me.' When the gold-winged bird heard this, it repented and blamed itself, saying: 'The Buddha's majestic spiritual power is profound and hard to fathom.' It invited the dragon into its palace, the dragon followed it in, and it then requested the dragon to receive the eight precepts.