Exodus 11:7
But against any of the children of Israel shall not a dog move his tongue, against man or beast: that ye may know how that the LORD doth put a difference between the Egyptians and Israel. But against any of the children of Israel shall not a dog move his tongue, against man or beast: that ye may know how that the LORD doth put a difference between the Egyptians and Israel.
Moses spoke these words as part of his last fearless warning to Pharaoh before leaving his presence, declaring the nature and effects of the last dreadful plague. About midnight the firstborn of Egypt would die, and there would be a great cry throughout all the land. At that same time no harm would come to any of the children of Israel, neither to people nor to animals.
That complete protection and quiet would be shown by the fact that not even a dog would move its tongue or bark against an Israelite, in striking contrast with the cry in Egypt. This was so that it would be known, especially by Pharaoh, that the Lord puts a difference and makes a distinction between the Egyptians and Israel. By that evident difference the Lord's power and judgment would be recognized and made known.