Bible on unanswered prayers

Genesis 16 vs 1: Non Sarai Abram’s wife bare him no children

Genesis 20 vs 7: And Abraham prayed unto God and God healed Abimelech and his wife, and his maidservants and they bare children

Genesis 21 vs 1: For Sarah conceived and bare Abraham a son in his old age at the set time of which God has spoken to him

1. There are some prayers that remain unanswered because God has refused to answer them.
2. Sarai, the wife of Abraham was barren, yet Abraham was a perfect man before God.
3. Sarai, the wife of Abraham was barren, yet the same Abraham prayed for Abimelech wives and maidservants who were barren, and they conceived and bore children; but the prayer of Abraham for his wife remained unanswered.
4. However, Sarai eventually conceived and bore a child.