Charles Spurgeon Commentary Genesis 22:2

"And he said, Take now thy son, thine only son, whom thou lovest, even Isaac, and get thee into the land of Moriah. And offer him there for a burnt-offering upon one of the mountains which I will tell thee of." — Genesis 22:2 (ASV)

Your only son,

"But, Lord, both Ishmael and Isaac are my sons, and each of them is the only son of his mother."

Isaac, whom thou lovest,

See how definitely God points out to Abraham the son who is to be the means of the great trial of his father's faith: Take now thy son, thine only son Isaac, whom thou lovest.

And get thee into the land of Moriah; and offer him there for a burnt offering upon one of the mountains which I will tell thee of.

It was usually the way, in God's commands to Abraham, to make him sail under sealed orders. When he was first commanded to leave his country and his relatives, and his father's house, he had to go to a land that God would show him. They have true faith who can go forth at God's command, not knowing where they are going. So Abraham did, and now the Lord says to him, Take Isaac, and offer him for a burnt offering upon one of the mountains which I will tell thee of.