Jesus knew that the Father had put all things under his power, and that he had come from God and was returning to God;
“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.