NET

21 The Lord will reveal himself to the Egyptians, and they will acknowledge the Lord’s authority at that time. They will present sacrifices and offerings; they will make vows to the Lord and fulfill them.

Darby

21 And Jehovah shall be known to the Egyptians, and the Egyptians shall know Jehovah in that day, and shall serve with sacrifice and oblation; and they shall vow a vow unto Jehovah, and perform it.

KJV

21 And the LORD shall be known to Egypt, and the Egyptians shall know the LORD in that day, and shall do sacrifice and oblation; yea, they shall vow a vow unto the LORD, and perform [it].