Exodus 10:23-27

They saw not one another, neither rose any from his place for three days: but all the children of Israel had light in their dwellings.

And Pharaoh called unto Moses, and said, Go ye, serve the LORD; only let your flocks and your herds be stayed: let your little ones also go with you.

And Moses said, Thou must give us also sacrifices and burnt offerings, that we may sacrifice unto the LORD our God.

Our cattle also shall go with us; there shall not an hoof be left behind; for thereof must we take to serve the LORD our God; and we know not with what we must serve the LORD, until we come thither.

But the LORD hardened Pharaoh’s heart, and he would not let them go.