Canon XXI
That monks are not to leave their monasteries and go into others.
A monk or nun ought not to leave the monastery to which he or she is attached, and betake themselves to others. But if one do this, he ought to be received as a guest. It is not however proper that he be made a member of the monastery, without the consent of his hegumenos.
It is not allowed to a monk or a nun to leave her own house and enter another; but if he (or she) enters let (him or her) be received as a guest; but let him (or her) not be admitted at all nor given hospitality contrary to the will of the superior.
The present canon does not allow a monk or a nun who goes to another house to be received into, nor even to be admitted as a guest, lest by force of necessity he be led astray to worldly things and so remain. Moreover it does not permit a woman to be admitted and received and reckoned in the number of the sisters without the consent of the superior.
It seems to me that in Aristenus an οὐκ must have crept into the text and that the first sentence should read as now but omitting the “not.” This makes him agree with Zonaras who says “the man must be received as a guest lest he go to a profane tavern and be forced to associate with those who have never learned how to live decently.” It is clear that the “superior” referred to is that of the house whence the monk or nun went forth.