“knew” is repeated from verse 13:1, “accenting the full consciousness of Jesus.  Jesus is fully conscious of his deity and Messianic dignity when he performs this humble act.” (RWP)

Morris sees the reference to the Father as being important. “He is no idle spectator at the Passion, but He works out His will there.” Jesus has come from God and is now returning to God; He was sent on a mission and now the mission is close to complete and upon its completion, He will return to His Father. This is it; He is about to go through that for which He came.

Although Jesus is about to do the most menial and humble of all tasks, He does it with full awareness of Who He is, where He came from, and to Whom He is going. Even though He is going to do the lowest of things, His position is the highest of all, by right. That is what makes His act so significant to us.

Again John states that he did not know the Messiah.  He could have meant that he didn’t personally know Him, since John grew up in the deserts of Judea and Jesus grew up in Galilee, but more probably it means that John didn’t know who it was that he was going to baptize with the Holy Spirit until he received the sign God had promised.  As Morris points out, “recognition came not from prior knowledge, but from supernatural revelation.” (NICNT p. 152) God does not usually give us full revelation of the things He has for us. He most often tells us just what we need to know.