Reading through the Bible together
The promised son is born “at the set time of which God had spoken to him” (v. 2). Compare Galatians 4:4. God never fails in His promises, and He is always right on time. Abraham also keeps his part of the covenant, circumcising Isaac on the eighth day, “as God had commanded him” (Gen 21: 4). Ishmael, now fourteen years old (cf. 16:16; 17:24-26), mocked at the birth of Isaac, no doubt feeling very superior, yet jealous at the joy this younger brother had brought into the home (21:6-8) and at the promises to be fulfilled through Isaac (v. 12; cf. 17:19). Despite the promises made to Ishmael and his descendants (17:20; 21:13), the covenant of the salvation of the human race through the promised Seed of the woman (Gen 3:15; 12:3; Gal 4:4-5) was to be through Isaac (Gen 21:12). Compare this situation with the allegory Paul describes in Galatians 4:21-31. What lessons are here for us? Why did God instruct Abraham to listen to the counsel of Sarah to “cast out this bondwoman and her son” (Gen 21:10-12; Gal 4:30)?
Despite Abraham’s earlier poor representation of right principles in the presence of Abimelech, king of Gerar in the land of the Philistines (Gen 20), Abimelech observes that God is with Abraham in all that he does (21:22), and he urges Abraham to make a covenant with him to return the kindness that Abimelech had extended to him (v. 23; cf. 20:14). Abraham was willing, but first reproved Abimelech in the matter of a disputed well. Abimelech insisted that he was unaware of the problem, and Abraham asked him to accept a gift of seven ewe lambs as witness that he had dug the well. Abraham also returned the kindness of Abimelech, giving him flocks and herds (21:27). They called the place Beersheba, the “well of the seven oaths.” Can observers say of us, despite our flaws, that God is with us in all that we do? Do they want to enter into a covenant relationship with us because God is with us?
Professor, Southern Adventist University