Exodus 3:15

15 God also said to Moses, ‘Say this to the Israelite people: “It is the Lord God who has sent me to you. He is the God that your ancestors worshipped. He is the God of Abraham, Isaac and Jacob.” That is my name for all time. All generations of my people must call me by that name.

3:15In English, we write God's special name as the Lord, with big letters. In Hebrew the name is YHWH. In English, this name is sometimes written as ‘Yahweh’ or ‘Jehovah’.