廣弘明集 9.64

9.64

玄妙內篇云。老子入關往維衛國。入清妙夫人口中。後剖左腋生。行七步曰。天上天下惟我為尊。於是乃有佛法。

The Xuanmiao neipian says: Laozi passed through the frontier pass and went to the kingdom of Vipaśyin. He entered the mouth of Lady Qingmiao. Later, he was born by splitting her left armpit, took seven steps, and said, "Above heaven and below heaven, only I am supreme." Thereupon the Buddha-Dharma came to be.