|Bereishit, Genesis 22, Vayeira|
I believe that Abraham understood that this was a Divine test. It was already clear to everyone that his older son Ishmael didn't have any of the necessary characteristics needed to lead, but Issac had to be put to a very serious test.
As parents, we sometimes must witness our children's struggles. We can't take their place or stop it. It wasn't easy for our forefather Abraham to cooperate administrating this frightening test on his beloved son. But he played the role perfectly, and that's why Gd praised him afterwards.
Abraham was then able to "retire" as "national leader," but he still had to marry off Issac. More about that next week in חיי שרה Chayei Sarah, the Lifetime of Sarah.