I believe that Abraham was hopeful that God would provide a sacrificial lamb but may have, also, had moments of doubt. However, as a God fearing man he found no other solution but to obey and trust God's demand, although with a heavy heart.
In telling the story of Abraham, in the Old Testament, you find where God has tested his faith on several occasions;Abraham always obedient and never unrewarded. Abraham trusted God's sovereignty and mercy.
Many times has God provided, especially in moments when I have needed His blessing the most. Has there been conditions? Sometimes. There has been times in which the condition called for making a decision that has tested my faith and trust in Him. At other times it has felt like a cool breeze caressing my face on a beautiful, lazy Sunday afternoon; a gift from God!
Praise be to God...God is Great...