In Genesis 22:2, we read that God told Abraham to sacrifice Isaac his beloved “only son”:
Then He said, “Take now your son, your only son Isaac, whom you love, and go to the land of Moriah, and offer him there as a burnt offering on one of the mountains of which I shall tell you.” (NKJV)
But instead of allowing Abraham to kill Isaac, God provided a ram as substitute. Ironically, Isaac was not literally Abraham’s only male offspring. Isaac had an older brother, Ishmael, born of Hagar. The reference in Genesis 22:2 to Abraham’s “only son…whom you love” is a clue which points to a deeper meaning in the passage.
In John 3:16, we learn that God so loved the world, He gave His one and only Son as a substitute for sinners. God the Father loved His only begotten Son (Ephesians 1:16) from before the creation of the universe, yet did not spare Him to save His people whom He loves. Jesus died as a substitute for all those who believe in Him just as the ram was a substitute for Isaac!
Genesis 22:2 looks forward to John 3:16
The modern Hebrew translation (Habrit Hakhadasha/Haderekh) of John 3:16 uses the same exact words in Hebrew: בנו היחיד translated his “only son” as your “only son” is found in Genesis 22:2.
This is just another way that we find that the Old Testament foreshadows and points to Jesus the Messiah and Savior of the world. The more you dig into the Bible, the more of these wonderful connections you find. (Although it helps a lot to be familiar with the original languages of the Bible, you could make the same connection I did using a good English translation, or a Bible concordance.)