In this week's Torah portion, after Abraham's victorious return from battle, we read:"Melchizedek the king of Salem brought out bread and wine, and he was a priest to the Most High God. And [Melchizedek] blessed him, and he said, "Blessed be Abram to the Most High God—Who possesses heaven and earth—and blessed be the Most High God, Who has delivered your adversaries into your hand." And [Abram] gave him a tithe from all."
Who was this Melchizedek? What sort of priest was he, and why did Abraham give him a tithe?
Taken alone, this tiny anecdote does indeed seem strange. The Torah tells us nothing else about this man and his relationship to Abraham.
The ancient Targumim (Aramaic interpretive translations) identify Melchizedek as Shem—son of Noah. Shem was one of the links in the chain who transmitted the G‑dly traditions that originated with Adam. These traditions were carefully handed down from generation to generation, and Shem—who headed an academy—was a key conductor of these teachings. The Midrash tells us that he was so perfect and so spiritually advanced that he was born circumcised.
So why did the priesthood pass from him to Abraham's children? The Talmud explains that this happened as a result of his having blessed Abraham before blessing G‑d in the verses above. This is reflected in the only other place in Scripture where Melchizedek is mentioned: in Psalms 110:4, where we read, ". . . you are a priest forever because of the speech of Melchizedek." Because of Melchizedek's ill-chosen speech, the priesthood was taken from him and given to the seed of Abraham forever.