Commentaries:
Since the law of clean and unclean was in force in Noah's time, and possibly in Abel's lifetime (Genesis 4:4), it was not made obsolete with the passing of the Old Covenant. This is a vital principle to remember regarding the Old and New Covenants: What did not originate with the Old Covenant did not die with it.
Richard T. Ritenbaugh
Clean and Unclean Meats