What message did Moses and Aaron first bring to Pharaoh from the LORD?

Answer: "Let My people go"

"This is what the LORD, the God of Israel, says: Let My people go, so that they may hold a feast to Me in the wilderness."

“After that, Moses and Aaron went to Pharaoh and said, “This is what the LORD, the God of Israel, says: ‘Let My people go, so that they may hold a feast to Me in the wilderness.’””— Exodus 5:1 (BSB)