Now this title is NOT TO SAY that Abraham WAS NOT THE MOST BELOVED MAN IN THE BIBLE IN GOD’S ESTIMATION, AND WAS TO BECOME KNOWN AS, "THE FATHER OF THE FAITHFUL".
Gen. 17:1"And when Abram was ninety years old and nine, the LORD appeared unto Abram, and said unto him, I am the Almighty God; walk before me, and be thou perfect.
2 And I will make my covenant between me and thee, and will multiply thee exceedingly.
3 And Abram fell on his face: and God talked with him, saying, 4 As for me, behold my covenant is with thee, and thou shall be a father of many nations. 5 Neither shall thy name any more be called Abram, but thy name shall be called Abraham; for a father of many nations have I made thee. 6 And I will make nations of thee, and kings shall come out of thee. 7 And I will establish my covenant between me and thee and thy seed after thee in their generations for an everlasting covenant. To be a God unto thee, and to thy seed after thee. 8 And I will give unto thee and to thy seed after thee, the land wherein thou art a stranger, all the land of Canaan, for an everlasting possession; and I will be their God.
9 And God said unto Abraham, Thou shalt keep my covenant therefore, thou, and thy seed after thee in their generations. 10 This is my covenant, which ye shall keep, between me and you and thy seed after thee; Every man child among you shall be circumcised.
11 And ye shall circumcise the flesh of your foreskin; and it shall be a token of the covenant betwixt me and you. 12 And he that is eight days old shall be circumcised among you, every man child in your generations, he that is born in the house, or bought with money of any stranger, which is not of your seed. 13 He that is born in your house, and he that is bought with money, must needs be circumcised: and my covenant shall be in your flesh for an everlasting covenant. 14 And the uncircumcised man child whose flesh of his foreskin is not circumcised, that soul shall be cut off from his people; he hath broken my covenant."
Now, as far as I can see and understand from my Bible, it seems to indicate that to have a relationship with another partner, other than your wife, constitutes ADULTERY, the breaking of the SEVENTH COMMANDMENT of God! Granted, this "scheme" to have a "firstborn" to inherit the promises given to Abraham seems to have been conceived by Sarai (Sarah), Abraham’s wife. She, somehow, thought this adulterous affair could be overridden by fulfilling the need for a "firstborn".
Continuing on in verse 15, "And God said unto Abraham, As for Sarai your wife, you shall not call her name Sarai, but Sarah shall her name be. 16 And I will bless her, and give her a son and give thee a son also of her: yea, I will bless her, and she shall be a mother of nations; kings of people shall be of her. 17 Then Abraham fell upon his face, and laughed, and said in his heart, shall a child be born unto him that is an hundred years old? And shall Sarah, that is ninety years old, bear?"
Now remember, God had already promised Abraham that he would be a "father of many nations" in Chapter 17:4. There was no mention of a surrogate, stepmother, replacing Sarah as the true mother to supply the Firstborn! What happens next seems to be contrived by Sarah!
Chapter 16:1,"Now Sarai, Abram’s wife bare him no children: and she had an handmaid, an Egyptian, whose name was Hagar. 2 And Sarai said unto Abram, behold now, the LORD hath restrained me from bearing: I pray thee, go in unto my maid; it may be that I may obtain children by her." (Abram’s thoughts were probably, "THAT SOUND’S LIKE A GOOD IDEA! So he fulfilled his "DUTY" to his wife.)
Verse 3,"And Sarai, Abram’s wife, took Hagar her maid the Egyptian, after Abram had dwelt ten years in the land of Canaan, and gave her unto her husband Abram to be his wife. 4 And he went in unto Hagar, and she conceived: and when she saw that she had conceived, her mistress was despised in her eyes."
God, in His Word, tells us in Deuteronomy 30:19"I call Heaven and earth to record this day against you that I have set before you LIFE AND DEATH, BLESSING AND CURSING, THEREFORE CHOOSE LIFE, THAT BOTH THOU AND THY SEED MAY LIVE.