Let's explore Hebrews 11. Why not?
17. By faith Abraham, when he was tried, offered up Isaac: and he that had received the promises offered up his only begotten son,
The verse says it was by faith he offered up Isaac. What for? As a burnt offering. He was to burn and kill Isaac. Did he suceed? Well, there is a surprise answer to that question. But the answer is they both walked off the mountain. So Abraham did nothing other than show up and be willing. By the way... The verse says he received "promises". Isaac certainly was one. What was the other?
But let's look at the account first hand:
Genesis 17:19-21 KJV
And God said, Sarah thy wife shall bear thee a son indeed; and thou shalt call his name Isaac: and I will establish my covenant with him for an everlasting covenant, and with his seed after him.
God said he was going to establish a covenant with Isaac's seed. That is Jacob, of course.
Gen 22:5 And Abraham said unto his young men, Abide ye here with the ass; and I and the lad will go yonder and worship, and come again to you.
Abraham said to his servants that they (Abraham and Isaac were coming back). Does that not seem strange? It shouldn't, because Abraham had faith in that God was going to establish a covenant with Isaac's seed.
THAT is some strong faith! God first said Isaac's seed would have the Covenant and Abraham still believed it even as he was going to sacrifice Isaac... So much that he said, we're coming back!
Back to Hebrews 11:
[18] Of whom it was said, That in Isaac shall thy seed be called: [19] Accounting that God was able to raise him up, even from the dead; from whence also he received him in a figure.
This is not a matter of Abraham believing he was going to lose his son whom he just loved so much (Im sure he did). It was a matter of the covenant being fulfilled.
Verse 19 suggests that Abraham believed he was going to go through with it and then God was going to bring him back.
Either way.... The faith was in the promised covenant. Yes God wanted to see if he would go through with it... I understand that. But the faith of Abraham was in that somehow they were both returning. It had nothing to do with any "works" were being done. Abraham wasn't worried about it.
Isaac, on the other hand, he might have been a little concerned at the moment....