God tested Abraham. He asked Abraham to sacrifice his only son, whom he loved! God knew what was most important to Abraham, what he would be tempted to withhold from the Lord.
When the rich young man asked what else he needed to do to receive eternal life, Jesus asked him to sell all he had give it to the poor (Matthew 19:16-22). God knew what was most important to this young man, what he would be tempted to withhold from the Lord.
God wants to know what the limits of our obedience are. You can be sure he knows what to ask for, what we would be tempted to withhold from him. We can also be sure that he plans to give us 100x back whatever we give him, plus eternal life!
Listen to this sermon from Genesis 22 about Obedience Without Limits!