Before the feast] St. John corrects the impression, which many have derived from the synoptic narratives, that the Last Supper was the actual Jewish Passover. It was, in fact, a Christian Passover, held the day before the Jewish feast (John 18:28), and probably not conformed in all respects to the Jewish ritual. There is, for example, no mention of a lamb, though it is possible that there may have been one. Unto the end] or, 'to the uttermost.'
Related Commentaries of John 13:1
John 13:1
1 Now before the feast of the passover, when Jesus knew that his hour was come that he should depart out of this world unto the Father, having loved his own which were in the world, he loved them unto the end.