Justin Martyr

The former is said to have circumcised the people a second time with knives of stone (which was a sign of this circumcision with which Jesus Christ Himself has circumcised us from the idols made of stone and of other materials), and to have collected together those who were circumcised from the uncircumcision, i.e., from the error of the world, in every place by the knives of stone, to wit, the words of our Lord Jesus. For I have shown that Christ was proclaimed by the prophets in parables a Stone and a Rock. Accordingly the knives of stone we shall take to mean His words, by means of which so many who were in error have been circumcised from uncircumcision with the circumcision of the heart, with which God by Jesus commanded those from that time to be circumcised who derived their circumcision from Abraham, saying that Jesus (Joshua) would circumcise a second time with knives of stone those who entered into that holy land.