A.T. Robertson Commentary Matthew 26:30

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

Sang a hymn (υμνησαντες). The Hallel, part of Ps 115-118. But apparently they did not go out at once to the Garden of Gethsemane. Jesus tarried with them in the Upper Room for the wonderful discourse and prayer in Joh 14-17. They may have gone out to the street after Joh 14:31. It was no longer considered obligatory to remain in the house after the passover meal till morning as at the start (Exodus 12:22). Jesus went out to Gethsemane, the garden of the agony, outside of Jerusalem, toward the Mount of Olives.