Albert Barnes Commentary Matthew 26:38

"Then saith he unto them, My soul is exceeding sorrowful, even unto death: abide ye here, and watch with me." — Matthew 26:38 (ASV)

My soul is exceeding sorrowful. His human nature—his soul—was much and deeply affected and pressed down.

Even unto death. This denotes extreme sorrow and agony. The sufferings of death are the greatest of which we have any knowledge; they are the most feared and dreaded by man; and those sufferings, therefore, represent extreme and indescribable anguish. The meaning may be expressed in this way: My sorrows are so great that under their burden I am ready to die; such is the anxiety of mind that I seem to bear the pains of death!

Tarry ye here, and watch with me. The word translated 'watch' means, literally, to abstain from sleep; then to be vigilant—to guard against danger. Here it seems to mean to sympathize with him, to unite with him in seeking Divine support, and to prepare themselves for approaching dangers.