You have heard that it was said by them of old time, You shall not kill; and whosoever shall kill shall be in danger of the judgment:
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Theophylact of Ochrid
AD 1107
Christ does not mention by whom this was said. For if He had said, "My Father said to the men of old, but I say to you," it would have appeared that He was giving laws in opposition to the Father. Again, if He had said, "I said to the men of old," this would have been hard to accept. Therefore He speaks indefinitely, "It was said to the men of old" (Deut. 5:17). He shows that the law has become antiquated by saying, "It was said to the men of old." Therefore, since the law has become old and antiquated and near the point of obliteration, it is necessary to leave it and to run to the new commandments.