Augustine of Hippo
Catena Aurea · Matthäusevangelium 23
Woe unto you, Scribes and Pharisees, hypocrites! for ye compass sea and land to make one proselyte, and when he is made, you make him two fold more the child of hell than yourselves.
(cont. Faust. xvi. 29. et cf. cont. Adimant. 16.) This He said not because proselytes were circumcised, but because they imitated the lives of those from following whom He had prohibited His disciples, saying, Do ye not after their works. Two things are observable in this command; first, the honour shewn to Moses’ teaching, (Matt. 23:3.) that even wicked men when sitting in his seat are compelled to teach good things; and that the proselyte is made a child of hell, not by hearing the words of the Law, but by following their doings. And twofold more than they for this reason, that he neglects to fulfil what he had undertaken of his own choice, having been not born a Jew, but of free will become a Jew.