Did you know that Abram's first child is Ishmael? And Isaac is Abraham's 2nd child?

The Hebrew scriptures are very clear that Ishmael was born to Abram after his wife, Sara, gave her maid-servant Hagar to Abram as a concubine. This was not God's will but poor Sara couldn't imagine any other way of the divine promise of an heir coming true, given that she was barren and past the age of child-bearing. Years later, the miracle happened and Isaac was born to Abrham and Sarah. The spiritual significance of this is detailed in the New Testament book of Galatians, chapter 4 verses 21-31. It pertains to being saved by law or by grace.