Charles H. Spurgeon on Psalms 110:7

I conceive that the "brook" here spoken of was not intended to give us the idea of a clear brook of refreshing water, which was to afford the Redeemer strength to endure the amazing conflict; as the drinking of the water enabled Gideon's chosen band of men to go forth to battle against the Midianites. No; in our Lord's case it was a polluted and turbid stream. Like the water of Marsh, which the Israelites could not drink, it was bitter; for sin had made it so. It bore along with it, as it flowed, the curse of the broken law, and the vengeance of offended justice, and the wrath of the eternal God. It was pain, sorrow, suffering, death. This was the "brook" of which he drank. The "cup" which his Father gave him to drink was filled with the bitter water of this "brook"; and he may be said to have first put his lips to it, when he declared to his disciples, in his way to Gethsemane, "My soul is exceedingly sorrowful, even unto death." But it is stated in the text that this "brook" was "in the way." It is described here as running by the path in which the Redeemer was going in order to the accomplishment of his great work of man's salvation; that work which he had engaged in the everlasting covenant to perform; and by the performance of which, man could alone be accepted of God. The sin of man was the source from whence this water issued; and it flowed along in the Saviour's "way, "through the wilderness of this world to his kingdom of glory in the next; as the brook Kidron, red with the blood of the typical sacrifices, flowed in his way to Calvary. Fountain Elwin, 1842.