Why did God change Abram and Sarai's names to Abraham and Sarah?
God changed their names when He brought them to the place of the covenant promises. The added letter H is associated with Yahweh or Jehovah, marking His covenant relationship. Thus Abram became Abraham and Sarai became Sarah, incorporating that H connotation.
Les explains that just as the number 5 was associated with grace, the letter H was associated with Yahweh or Jehovah. When God brought Abram and Sarai to the place of the covenant promises, He changed their names to Abraham and Sarah, and the H is included in both. In Genesis 17:15 God says Sarai's name shall not be called Sarai but Sarah, and He will bless her. Verse 16 adds that she shall be a mother of nations, and kings of people shall come from her. Les notes Abraham had already been waiting about fifty years for the promised son, since his first call likely came when he was fifty and Isaac would be born when he was a hundred.
And God said unto Abraham, As for Sarai thy wife, thou shalt not call her name Sarai, but Sarah shall her name be.
More Questions
What change did God make to Sarai's name in Genesis 17:15?
God also changed Sarai's name to Sarah in Genesis 17:15, doing the same thing as with Abram by adding the letter H.
What does the letter added to Abram's name to make Abraham mean?
The difference in the names Abram and Abraham is the Hebrew letter of the alphabet that refers to grace, so God's grace is implied by changing Abram to Abraham and Sarai to Sarah.