"Abraham looked up and there in a thicket he saw a ram caught by its horns. He went over and took the ram and sacrificed it as a burnt offering instead of his son." NIV translation
At just the right time, God provided a ram to replace Isaac on the sacrificial altar. That brings to mind the question of: Why a ram and not a lamb? A lamb is a baby while a ram is considered an adult and the lamb can only become an adult through the passage of time. This is a reminder of the fact that Jesus would come from the line of Abraham but only at the proper time. He would come as a baby (lamb) but would be sacrificed as an adult (ram).
"So Abraham called that place The Lord Will Provide. And to this day it is said, 'On this mountain of the Lord it will be provided.'" NIV translation
God sent Abraham to Mt. Moriah and Abraham now calls it The Lord Will Provide.
So, how do we get to where we are today with the place being called Jerusalem?
In Hebrew, Abraham called the place Adonai Yireh (God will provide). Before that, the city was named Salayim (Shelem) which means "perfect" by Shem (Noah's son) after the flood.
The two would later be combined to form the name Jerusalem which refers to God's perfect provision. The name also points to the fact that God will provide the perfect city in the last days as we see it descending from heaven in Revelation 21.
"The angel of the Lord called to Abraham from heaven a second time and said, 'I swear by myself, declares the Lord, that because you have done this and have not withheld your son, your only son, I will surely bless you and make your descendants as numerous as the stars in the sky and as the sand on the seashore. Your descendants will take possession of the cities of their enemies, and through your offspring all nations on earth will be blessed, because you have obeyed me.' Then Abraham returned to his servants, and they set off together for Beersheba. And Abraham stayed in Beersheba." NIV translation
An angel declared the renewal of God's covenant with Abraham. The angel told him that God would bless him and we are reminded that blessed simply means "no worries". In effect, God was telling Abraham that his people would not have to worry because He was going to provide the perfect sacrifice (Jesus) at the perfect time.