Genesis 16:1-3
“Now Sarai, Abram’s wife, had not been able to bear children for him. But she had an Egyptian servant named Hagar. So Sarai said to Abram, ‘The Lord has prevented me from having children. Go and sleep with my servant. Perhaps I can have children through her. And Abram agreed with Sarai’s proposal. 3 So Sarai, Abram’s wife, took Hagar the Egyptian servant and gave her to Abram as a wife. (This happened ten years after Abram had settled in the land of Canaan.)”
Genesis 18:8-15
“8 As they ate, Abraham waited on them in the shade of the trees. 9“Where is Sarah, your wife?” the visitors asked. “She’s inside the tent,” Abraham replied. 10 Then one of them said, “I will return to you about this time next year, and your wife, Sarah, will have a son!” Sarah was listening to this conversation from the tent. 11 Abraham and Sarah were both very old by this time, and Sarah was long past the age of having children. 12 So she laughed silently to herself and said, “How could a worn-out woman like me enjoy such pleasure, especially when my master—my husband—is also so old?”
13 Then the LORD said to Abraham, “Why did Sarah laugh? Why did she say, ‘Can an old woman like me have a baby?’ 14 Is anything too hard for the LORD? I will return about this time next year, and Sarah will have a son.” 15 Sarah was afraid, so she denied it, saying, “I didn’t laugh.” But the LORD said, “No, you did laugh”
Genesis 21:1-7
1 The LORD kept his word and did for Sarah exactly what he had promised. 2 She became pregnant, and she gave birth to a son for Abraham in his old age. This happened at just the time God had said it would. 3 And Abraham named their son Isaac. 4 Eight days after Isaac was born, Abraham circumcised him as God had commanded. 5 Abraham was 100 years old when Isaac was born.
6 And Sarah declared, “God has brought me laughter. All who hear about this will laugh with me. 7 Who would have said to Abraham that Sarah would nurse a baby? Yet I have given Abraham a son in his old age!”
Hebrews 11:11-12
11 It was by faith that even Sarah was able to have a child, though she was barren and was too old. She believed that God would keep his promise. 12 And so a whole nation came from this one man who was as good as dead—a nation with so many people that, like the stars in the sky and the sand on the seashore, there is no way to count them