What does Genesis 26:3 mean?

A famine has forced Isaac and his family to migrate in search of more fertile territory. The Lord has commanded them not to travel to Egypt, as many people did in this time. There the Nile kept the land well-watered even during some seasons of drought. This command from God might have been due to lingering resentment over what Abraham, Isaac's father, had done to the Pharaoh many decades earlier (Genesis 12:18–20). It might also be a simple issue of God proving His ability to provide in His own way, and His own time.

Instead, the Lord insists that Isaac keep his family in the land of Gerar, ruled by the king of the Philistines. The Lord delivers to Isaac a powerful message: I will be with you. I will bless you. I will give all these lands to you and to your offspring. That sounds familiar, since these are the same promises the Lord had given to Isaac's father Abraham (Genesis 12:1–3). In fact, the Lord makes that point: I will establish the same oath with you that I did with your father.

This is a huge moment in Isaac's life. During Abraham's lifetime, God's relationship with His people had been defined by God's relationship with Abraham. Now that Abraham was dead, Isaac had to wonder at times if God would deal in the same way with Him. God makes clear in this moment that all of the same promises still hold true. He will be with Isaac.