In these verses there is an evident allusion to the idolatrous worship in Egypt.
Among the Egyptians, almost everything in nature was the object of their idolatry; among beasts were oxen, heifers, sheep, goats, lions, dogs, monkeys, and cats; among birds, the ibis, crane, and hawk; among reptiles, the crocodile, serpents, frogs, flies, and beetles; all the fish of the Nile, and the Nile itself; besides the sun, moon, planets, stars, fire, light, air, darkness, and night.
These are all included in the very circumstantial prohibition in the text, and very forcibly in the general terms of Ex 20:4, the reason of which prohibition becomes self-evident, when the various objects of Egyptian idolatry are considered.