法苑珠林 88.23

88.23

又成實論云。自妻非處。謂口及大便處。及一切女人為父母兒所護。出家女人等為法護故亦名邪婬。若無主女人眾人前自來為妻。如法者不犯。

Furthermore, the Tattvasiddhi-śāstra says: Improper places with one's own wife refer to the mouth and the anus. Moreover, all women who are guarded by parents or children, and renunciant women who are guarded by the Dharma, are also called sexual misconduct. If an unattached woman comes forward of her own accord before the assembly to become a wife according to the Dharma, there is no violation.