John Lightfoot on Mark 14:26

[And when they had sung an hymn.] I. "What difference is there between the first Passover and the second?" [that is, the Passover of the first month and of the second, Numbers 9]. "In the first, every one is bound under that law, 'Leaven shall not be seen nor found among you.' In the second, 'Leaven and unleavened bread may be with a man in his house.' In the first, he is bound to a hymn when he eats the Passover. In the second, he is not bound to a hymn when he eats it. In both, he is bound to a hymn while he makes or kills. Both are to be eaten roast, and with unleavened bread, and bitter herbs, and both drive away the sabbath." The Gemarists ask, "Whence this is, that they are bound to a hymn, while they eat the Passover? R. Jochanan in the name of R. Simeon Ben Josedek saith, The Scripture saith, 'You shall have a song, as in the night when a feast is kept,' Isaiah 30:29. The night which is set apart for a feast is bound to a hymn: the night which is not set apart for a feast is not bound to a hymn." The Gloss writes thus; "As ye are wont to sing in the night when a feast is kept: but there is no night wherein they are obliged to a song, besides the night when the Passover is eaten."

II. That hymn is called by the Rabbins the Hallel; and was from the beginning of Psalm 113, to the end of Psalm 118, which they cut in two parts; and a part of it they repeated in the very middle of the banquet, and they reserved a part to the end.

How far the former portion extended, is disputed between the schools of Shammai and Hillel. That of Shammai saith, Unto the end of Psalm 113. That of Hillel saith, Unto the end of Psalm 114. But these things must not stop us. The hymn which Christ now sang with his disciples after meat was the latter part. In which, as the Masters of the Traditions observe, these five things are mentioned: "The going out of Egypt. The cutting in two of the Red Sea. The delivery of the law. The resurrection of the dead: and the sorrows of the Messias. The going out of Egypt, as it is written, 'When Israel went out of Egypt.' The cutting in two of the Red Sea, as it is written, 'The sea saw it, and fled.' The delivery of the law, as it is written, 'The mountains leaped like rams.' The resurrection of the dead, as it is written, 'I will walk before the Lord in the land of the living.' And the sorrows of the Messias, as it is written, 'Not unto us, Lord, not unto us.'"

[They went out into the mount of Olives.] They were bound by traditional canons to lodge within Jerusalem. "On the first Passover, every one is bound to lodge also on the second Passover he is bound to lodge." The Gloss thus: "He that keeps the Passover is bound to lodge in Jerusalem the first night." But it is disputed, whether it be the same night wherein the lamb is eaten; or the night first following the feast day. See the place: and let not the lion of the tribe of Judah be restrained in those cobwebs [Pesach. fol. 95 .2.]