A king of Salem and a priest. When Abraham returned from battle after rescuing Lot, Melchizedek greeted him and gave him a blessing in honor of his victory (Genesis 14:18-20). In return Abraham offered him tithes because of his priesthood. In a Psalm devoted to the dual role of priest and king, David exclaimed, "Yahweh has sworn an oath which he never will retract, You are a priest of the order of Melchizedek and forever" (Psalm 110:4). There are only two references to this priest-king in the Old Testament. In the New Testament the Epistle to the Hebrews associates Christ's priesthood with Melchizedek's by quoting in three successive chapters the invocation from Psalm 110: "You are a priest of the order of Melchizedek and forever." This is also the biblical basis for the Catholic doctrine that, once a man is ordained a priest, his priesthood, like Christ's "in the line of Melchizedek," is forever (Hebrews 5, 6, 7).