The Council in Trullo (Quinisext Council, 692 AD)

Those women who choose the ascetic life and are settled in monasteries may by no means go forth of them. If, however, any inexorable necessity compels them, let them do so with the blessing and permission of her who is mother superior; and even then they must not go forth alone, but with some old women who are eminent in the monastery, and at the command of the lady superior. But it is not at all permitted that they should stop outside.

And men also who follow the monastic life let them on urgent necessity go forth with the blessing of him to whom the rule is entrusted.

Wherefore, those who transgress that which is now decreed by us, whether they be men or women, are to be subjected to suitable punishments.

Ancient Epitome of Canon XLVI.

A nun shall not go out of her convent without the consent of her superior, nor shall she go alone but with an older one of the order. It is in no case permitted to her to spend the night outside. The same is the case with a monk; he cannot go out of the monastery without the consent of the superior.