12 Now, in the third water-pot, to Abraham, as I have mentioned before, it was said, “In your seed shall all nations be blessed.” And who does not see whose figure Abraham's only son was, he who bore the wood for the sacrifice of himself, to that place whither he was being led to be offered up? For the Lord bore his own cross, as the Gospel tells us. This will be enough to say concerning the third water-pot.
Source: Tractates on the Gospel of John (New Advent)