4 Let us hear how the Lord answered them, praising Abraham to their condemnation. “Jesus says unto them, If you are Abraham's children, do the works of Abraham. But now ye seek to kill me, a man that has told you the truth, which I have heard of God: this did not Abraham.” See, he was praised, they were condemned. Abraham was no manslayer. I say not, He implies, I am Abraham's Lord; though did I say it, I would say the truth. For He said in another place, “Before Abraham was, I am”; and then they sought to stone Him. He said not so. But meanwhile, as you see me, as you look upon me, as alone you think of me, I am a man. Wherefore, then, wish you to kill a man who is telling you what he has heard of God, but because you are not the children of Abraham? And yet He said above, “I know that you are Abraham's children.” He does not deny their origin, but condemns their deeds. Their flesh was from him, but not their life.
Source: Tractates on the Gospel of John (New Advent)