Through Abraham’s faithful walk with God he faced many challenges related to God’s Promises. Where was the son promised him? Sarah struggled with this too. A point came where they conspire together to get God’s work done for Him.
Now Sarai, Abram’s wife, had borne him no children. But she had an Egyptian maidservant named Hagar; so she said to Abram, “The LORD has kept me from having children. Go, sleep with my maidservant; perhaps I can build a family through her.” Abram agreed to what Sarai said. Genesis 16:1-2
Now, this happened before the destruction of Sodom. And just after God made a covenant with Abraham that sealed his future. And before circumcision was instituted.
Antonio María Esquivel, “Hagar and Ishmael in the Desert,”.