Albert Barnes Commentary Matthew 26:37

"And he took with him Peter and the two sons of Zebedee, and began to be sorrowful and sore troubled." — Matthew 26:37 (ASV)

And he took with him Peter and the two sons of Zebedee. That is, James and John (Matthew 10:2). On two other occasions he had favored these disciples in a particular manner, permitting them to go with him to witness his power and glory, namely, at the healing of the ruler's daughter (Luke 8:51) and at his transfiguration on the mount (Matthew 17:1).

Sorrowful. Affected with grief.

Very heavy. The word in the original is much stronger than the one translated sorrowful. It means to be pressed down or overwhelmed with great anguish. This was produced, doubtless, by a foresight of his great sufferings on the cross in making an atonement for the sins of men.