廣弘明集 9.82

9.82

依十誡十四持身經云。北方禮一拜。北方為始。東向而周十方。想見太上真形。

According to the Scripture of the Ten Precepts and Fourteen Ways of Maintaining the Body, it says: ‘Make one prostration toward the north; the north is the beginning; then proceed toward the east to encompass the ten directions, visualizing the true form of the Most High.’