Exodus 6:3
And I appeared unto Abraham, unto Isaac, and unto Jacob, by the name of God Almighty, but by my name JEHOVAH was I not known to them. And I appeared unto Abraham, unto Isaac, and unto Jacob, by the name of God Almighty, but by my name JEHOVAH was I not known to them.
Abraham, Isaac, and Jacob knew God by the title God Almighty. To Moses, by contrast, God was now making himself known by his name Jehovah. That unveiling of Jehovah disclosed his power to carry out his covenant, and it was to become known through Israel's deliverance from Egypt.
In that same setting God recalled his covenant to give Canaan to the patriarchs, declaring that he had heard Israel's groaning under bondage and remembered that covenant. The declaration came as reassurance to Moses when Israel's suffering had increased and he was distressed, affirming that the covenant would be faithfully fulfilled. Pharaoh himself would be compelled to release Israel. That assurance rested on God's continuing faithfulness to the covenant he had made with Abraham, Isaac, and Jacob.