Exodus:12:29-30 At midnight the LORD struck down all the firstborn in Egypt, from the firstborn of Pharaoh, who sat on the throne, to the firstborn of the prisoner, who was in the dungeon, and the firstborn of all the livestock as well. Pharaoh and all his officials and all the Egyptians got up during the night, and there was loud wailing in Egypt, for there was not a house without someone dead.
Previously we read that God hardened Pharaoh’s heart then threatens to kill his firstborn son. Here we see God carrying out the threat. However, he not only killed Pharaoh’s firstborn son, he killed all the firstborn sons in Egypt. To add to it, he also killed the firstborn of all the livestock.
Wait a minute! Exodus 9:6 states “And the next day the LORD did it: All the livestock of the Egyptians died, but not one animal belonging to the Israelites died.” If God already killed all the livestock, how were there firstborn livestock?