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.
With these words, the Lord reassured Moses that He would stand with him and give him the strength and power to lead the Israelites out of Egyptian slavery. He had already given Moses this promise at the burning bush (see Exodus 3:2,12), but Moses needed encouragement after Pharaoh rejected his first requested to release the Israelites.
God declared to Moses that He was prepared to perform miracles for His people that they had never seen before. As Jehovah, He was the infinite and self-existent God who caused everything to happen and to whom all things must eventually be traced. He would not fail in His determination to bring freedom to His people.
When God makes a promise, it’s as good as done.