Genesis 17:17
Then Abraham fell on his face and laughed and said to himself, "Shall a child be born to a man who is a hundred years old? Shall Sarah, who is ninety years old, bear a child?"
Jan Provoost, Abraham, Sarah, and the Angel, Oil on panel, 1520s
The Story of Abraham, Sarah, & Issac
God had promised Abraham he would be the father of many nations, but Sarah was old and barren. Due to their doubt and impatience, Sarah suggested Abraham have a child with her maidservant, Hagar, which resulted in the birth of Ishmael, but this was not the promised son.
Later, God reaffirmed the promise, and despite Sarah’s disbelief, she miraculously conceived and gave birth to a son named Isaac, meaning “laughter”.