Doing G-d’s will, over and above what one personally loves most, is the essence of a Jew’s purpose in this world – and Abraham exemplified that purpose both when he left for an unknown destination (the land of Israel) and when he went to sacrifice Isaac.
The challenge to leave his land, however, was seemingly mitigated by G-d’s guarantees that he would become rich, famous, blessed and the source of blessing for the world etc. One could wonder how this was indeed a test.
However, Abraham only did it because G-d commanded him – he ignored the guarantees of reward.
With that insight, it’s possible to resolve a difficult Midrash that says . . . it’s hard to determine which test, leaving his land or the binding of Isaac, was dearer to G-d.
Why was this hard to determine? Isn’t it clear that the binding must have been dearer? How could someone ignore their son without the most tremendous self-control?
But G-d’s guarantees to Abraham included bearing children. Just exactly how could Abraham leave his land and ignore the fact that he would have children considering he was already old and had had none so far? That would also be superhuman!
Therefore, there is room to think that these two challenges are equivalent (even if in the end, the Midrash explains that the binding of Isaac was, in fact, dearer).
"Go for yourself, from your land… I will make you a great nation; I will bless you, make your name great and you shall be a blessing." Genesis 12:1-2, from this week's Torah portion, Lech Lecha, Genesis 12:1-17:27