Exodus 8:25-27

And Pharaoh called for Moses and for Aaron, and said, Go ye, sacrifice to your God in the land.

And Moses said, It is not meet so to do; for we shall sacrifice the abomination of the Egyptians to the LORD our God: lo, shall we sacrifice the abomination of the Egyptians before their eyes, and will they not stone us?

We will go three days' journey into the wilderness, and sacrifice to the LORD our God, as he shall command us.