What does Genesis 15:4 mean?

In the previous verses, the word of the Lord came to Abram in a vision. Abram took the opportunity to ask God—who had promised to make of him a great nation—some hard questions. As things stand now, Abram's questions point out, his heir will be a servant, not a son. If God is not going to give him children, how is God going to fulfill these promises?

First, in this verse, God begins to reassure Abram that He still intends to keep His promises: Abram's heir will be his actual, literal son, his own flesh and blood. The Hebrew phrase used here is aser' yē'sē mi mē'e kā hu yi'ra'se kā. This literally means "one who will come from your own body will be your heir." God is doubling down on iHs promise to provide Abram with a natural-born child. This reply is important for all who trust God to remember. The fact that God has not yet given what He promised does not mean He will not. Time does not empty God's promises of their power, even if waiting challenges our patience and, sometimes, our faith.