Isaiah 19:21 in the King James Version
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.
Context
20 It will be for a sign and for a witness to the LORD of Armies in the land of Egypt; for they will cry to the LORD because of oppressors, and he will send them a savior and a defender, and he will deliver them.
21 The LORD will be known to Egypt, and the Egyptians will know the LORD in that day. Yes, they will worship with sacrifice and offering, and will vow a vow to the LORD, and will perform it.
22 The LORD will strike Egypt, striking and healing. They will return to the LORD, and he will be entreated by them, and will heal them.