13 Likewise, let it not surprise you that He says, “In your law it is written that the testimony of two men is true,” that any man should hence suppose that this was not also the law of God, because it is not said, In the law of God: let him know that, when it is said thus, In your law, it is just as if He said, “In the law which was given to you;” given by whom, except by God? Just as we say, “Our daily bread;” and yet we say, “Give us this day.”
Source: Tractates on the Gospel of John (New Advent)