首楞嚴義疏注經 1.239

1.239

身中無救，身外必然，不遇尊言，莫悟斯旨，故稽首於佛，謝非立是也。以頭至地稽留少時，故名稽首。

Since [the mind] cannot be salvaged inside the body, it must be outside the body. Without encountering the Honoured One's words, he would not have understood this principle; therefore he bowed his head to the Buddha, confessing his error and establishing what is correct. Bringing one's head to the ground and lingering for a short time is called "bowing the head to the ground" (*jishou*).