Leviticus 11:16

And the owl, and the night hawk, and the cuckow, and the hawk after his kind,

The owl, the night hawk, the cuckoo, and the hawk after his kind are named among the birds whose flesh was unclean and prohibited as food. The prohibition belongs to the law given through Moses to Israel, part of the health and sanitary laws in Leviticus 11:1-47, which taught the distinction between clean and unclean. That law forbade eating any unclean thing, including swine's flesh and the flesh of certain other animals, as unfit for food and not the best food.

The restriction was not an arbitrary exercise of authority but was given for health to preserve the life and health of the people. It was intended to guard against impurities in the blood and shortened life, since such food fills the blood with impurities and shortens life. By forbidding unclean animals it kept the blood pure through simple, healthful food and protected health.

The Pharisees perverted these restrictions by not leaving them as given but going beyond what was required and imposing additional rules of external and ritual cleanliness. In their unwarranted extremes they required straining all water used lest it contain the smallest insect that might be classed with the unclean animals. Jesus condemned them for extending rules about ritual cleanliness beyond what God required and treating such minor matters as more important than serious sins.

The Hebrews were commanded to obey these prohibitions. Daniel and his companions refused the king's meats because this food included meats the law pronounced unclean. They did so seeking to keep their minds clear and their bodies fit for God's service.