Buried all their first-born, which the Lord had smitten among them. Literally, "were burying those whom the Lord had smitten among them, viz; all the first-born." The fact that the Egyptians were so universally employed about the funeral rites of their first-born—rites to which they paid such extreme attention—seems to be mentioned here as supplying one reason at least why the Israelites began their outward march without opposition.
It is in perfect accordance with what we know of the Egyptians, that all other passions and interests should give place for the time to the necessary care for the departed. Upon their gods also the Lord executed judgments.
See on Exodus 12:12, and cf. Isaiah 19:1. The false deities of Egypt, having no existence except in the imaginations of men, could only be affected within the sphere of those imaginations, i.e; by being made contemptible in the eyes of those who feared them.