Charles Ellicott Commentary Matthew 26:30

"And when they had sung a hymn, they went out unto the mount of Olives." — Matthew 26:30 (ASV)

And when they had sung a hymn—This conclusion to the supper seems to coincide (though harmonizing the Gospel accounts at this point is difficult) with the words Rise, let us go hence (John 14:31). If so, it suggests that the conversation in John 14 occurred either between the departure of Judas and the institution of the Lord’s Supper, or between that institution and the concluding hymn. This hymn was probably the traditional Passover series of psalms (Psalms 115–118), and the word implies a chant or musical recitative. Psalms 113 and 114 were commonly sung during the meal. The Greek word can also mean “when they had sung their hymn,” suggesting it was a specific, customary song.

They went out into the Mount of Olives—We should picture the Passover group dispersing, and the fear and foreboding that pressed upon the minds of all as they left the chamber. They made their way under the cold moonlight through the streets of Jerusalem, down to the Kidron Valley and up the western slope of the Mount of Olives. Luke records that His disciples followed Him—some near, and some, perhaps, at a distance. The discourses reported in John 15–17, which must be assigned to this period, seem to imply that they paused from time to time. During these stops, the Master poured out His heart to His disciples and uttered intercessions for them. John, who had “lain on His bosom” at the supper, would naturally have been nearest to Him, which may partly explain why such a full report of what was spoken appears only in his Gospel.