Exodus 9:4, commentary and pictures

The Lord would sever between the cattle of Israel and the cattle of Egypt, so that nothing belonging to Israel, of all that was the children's of Israel, would die. The exemption of the Hebrews from the evil was distinct, setting Israel's cattle apart from Egypt's during the livestock plague. It was spoken beforehand as a forewarning to Pharaoh of the coming plague if he refused to let Israel go. The warning was delivered through Moses and Aaron calling Pharaoh to let Israel go to serve God, with the plague threatened if he refused and continued to hold them.

The threatened and then sent plague was murrain upon the Egyptian cattle, upon all the Egyptian cattle out in the field. The distinction was fulfilled when the afflicted, plague-struck Egyptian cattle died while the Israelites' cattle remained unharmed. The plague came as predicted, and this fulfillment demonstrated that Moses's declaration was true. The division was complete: none of the cattle of Israel died or were even afflicted.

Pharaoh verified this by sending messengers to the homes of the Israelites, who reported that they had entirely escaped with not one dead and nothing dead. Even after verification Pharaoh's heart was hardened and he remained obstinate and refused to let Israel go. He was encouraged in persistency by the priests and magicians. The murrain on cattle came before the plague of boils on man and beast and the plague of hail mingled with fire. The distinction demonstrates God's protection of Israel and His judgment on Egypt's animal worship, destroying the sacred animals and displaying His supremacy over the idols.