Abraham, Joseph, and Moses » Melchizedek

In the time of Abraham, the city of Salem—modern-day Jerusalem—was a place of wickedness, abomination, and all manner of immoral behavior. An unusual child named Melchizedek was born there. From his youth he had a great trust in Jesus, and he had escaped death by stopping the mouths of lions and quenching the violence of fire.

Sources:
• Wright, Dennis A. “None Were Greater”: A Restoration View of Melchizedek. Ensign: The Magazine of The Church of Jesus Christ of Latter-Day Saints, February 1998.

Melchizedek had Jesus's approval, and was ordained as a high priest in the order of the Son of God. Like Enoch before him, he was given the power to break mountains and turn rivers from their course. Melchizedek preached repentance to the people of Salem, and they repented and became a righteous people. Melchizedek reigned as their king and there was peace in the land.

Sources:
• Wright, Dennis A. “None Were Greater”: A Restoration View of Melchizedek. Ensign: The Magazine of The Church of Jesus Christ of Latter-Day Saints, February 1998.
• Old Testament Student Manual Genesis-2 Samuel, (1980), 64–72

Abraham became rich while in Egypt. He then returned to the land of Canaan where he met Melchizedek at the valley of Shaveh. Melchizedek blessed Abraham and ordained him to the high priesthood. Melchizedek brought forth bread and wine, blessed it and shared it with Abraham.

Sources:
• Old Testament Stories, (1980), 33–37
• "Abraham: Father of the Faithful". Ensign: The Magazine of The Church of Jesus Christ of Latter-Day Saints, February 2006.
• Old Testament Seminary Teacher Manual, 2014 - Lesson 22: Genesis 13–14

"I believe all you have taught me about the priesthood and the coming Son of Man," said Abraham to Melchizedek. Now Melchizedek was the keeper of the storehouse of God. Abraham proved his faith by paying him a 10% tithe of all his riches, just as today we pay 10% of our income to the President of the Church who is the keeper of God's storehouse in our day.

Sources:
• Wright, Dennis A. “None Were Greater”: A Restoration View of Melchizedek. Ensign: The Magazine of The Church of Jesus Christ of Latter-Day Saints, February 1998.
• Hales, Robert D. "Tithing: A Test of Faith with Eternal Blessings". General Conference Report, October 2002.
• True to the Faith, (2004), 180–82

Many other high priests have come and gone since the time of Melchizedek, but none were greater. This is why the higher priesthood of the Church is called the Melchizedek priesthood to this day. After Abraham went on his way, Melchizedek and the people of Salem remained so righteous that, like Zion, their entire city was taken up to heaven.

Sources:
• Wright, Dennis A. “None Were Greater”: A Restoration View of Melchizedek. Ensign: The Magazine of The Church of Jesus Christ of Latter-Day Saints, February 1998.
• Kocherhans, Gib. "The Name “Melchizedek”: Some Thoughts on Its Meaning and the Priesthood It Represents". Ensign: The Magazine of The Church of Jesus Christ of Latter-Day Saints, September 1980.