佛祖統紀 34.12

34.12

菩薩乘六牙白象發兜率宮。放大光明普照十方。以四月八日明星出時。降神母胎。從右脇入（因果經）。

Riding a six-tusked white elephant, the bodhisattva departed from the Tuṣita palace, emitting a great illumination that shone universally throughout the ten directions. On the eighth day of the fourth month, at the time the bright morning star arose, he lowered his spirit into his mother's womb, entering from her right flank (Sūtra of Cause and Effect).