Then the LORD said unto Moses, Go in unto Pharaoh, and tell him, Thus saith the LORD God of the Hebrews, Let my people go, that they may serve me. The Lord God of the Hebrews - It is very likely that the term Lord, יויה Yehovah, is used here to point out particularly his eternal power and Godhead; and that the term God, אלהי Elohey, is intended to be understood in the sense of Supporter, Defender, Protector, etc. Thus saith the self-existent, omnipotent, and eternal Being, the Supporter and Defender of the Hebrews, "Let my people go, that they may worship me."
Related Commentaries of Exodus 9:1
Exodus 9:1
1 Then the LORD said unto Moses, Go in unto Pharaoh, and tell him, Thus saith the LORD God of the Hebrews, Let my people go, that they may serve me.