Exodus 5:8

5:8 But you must require of them the same quota of bricks that they were making before. Do not reduce it, for they are slackers. That is why they are crying, ‘Let us go sacrifice to our God.’

Exodus 8:8

8:8 Then Pharaoh summoned Moses and Aaron and said, “Pray to the Lord that he may take the frogs away from me and my people, and I will release the people that they may sacrifice to the Lord.”

Exodus 8:28

8:28 Pharaoh said, “I will release you so that you may sacrifice to the Lord your God in the desert. Only you must not go very far. Do pray for me.”