Mormon Doctrine, pg. 13; ““Abraham first received the gospel by baptism (which is the covenant of salvation); then he had conferred upon him the higher priesthood, and he entered into celestial marriage (which is the covenant of exaltation), gaining assurance thereby that he would have eternal increase; finally he received a promise that all of these blessings would be offered to all of his mortal posterity. (Abra. 2:6-11; D. & C. 132:29-50.).”
Genesis 15:1, 6; “After these things the word of the LORD came unto Abram in a vision, saying, Fear not, Abram: I am thy shield, and thy exceeding great reward. 6 And he believed in the LORD; and he counted it to him for righteousness.”
Who conferred this “priesthood” onto Abraham? The Bible tells us the priesthood wasn’t instituted until the time of Moses and his brother Aaron. The “covenant of exaltation”, aka polygamy, got Abraham into trouble. Remember Hagar was the bondwoman (meaning cast out), while Sarah was the free woman (meaning promise).