Musar zu Bereschit 22:9

The Yalkut on Bereshit (22,9) וישם אותו על המזבח describes both Abraham looking at Isaac, and Isaac looking towards Heaven. Both were crying. The Yalkut presents a most moving picture of the great quantity of tears which covered Abraham from head to toe. All this in order to implore G–d to save Isaac. Abraham told his son that seeing he had wept so many tears, G–d has provided a different offering in his place. At that moment Isaac broke out in bitter cries proclaiming: "I raise my eyes towards the mountains, whence will my salvation come?" (Psalms 121,1). All this proves that both Abraham and Isaac had been willing to go through with the sacrifice, but how could they have been described as having served the Lord with joy, as is required?!