When Abram was 75 years old, God made him a promise.
“He took him outside and said, ‘Look up at the sky and count the stars—if indeed you can count them.’ Then he said to him, ‘So shall your offspring be.’” Genesis 15:5
Abram was 86 when he and Sarai took matters into their own hands, impatient with waiting for God to fulfill his promise. Ishmael was born. But that was not how God intended to keep his promise.
Abraham was 99 when God gave his wife and him new names and again promised he would have offspring as many as the stars—with his wife Sarah.
Abraham was 100 years old and Sarah was 90, when Isaac was born.
God fulfilled his promise to Abraham, in spite of Abraham and Sarah’s advanced age. In spite of their efforts to “help” God. And it took 25 years from the first promise. If you read their story in Genesis, both Abraham and Sarah laughed at God’s promise, unable to conceive (ha) how it could be. But they somehow believed—in hope—and God did what he said he was going to do.