A cherub, also pl. cherubim, is a winged angelic being who is considered to attend on the Abrahamic God in biblical tradition. The concept is represented in ancient Middle Eastern art as a lion or bull with eagles' wings and a human face, and regarded in traditional Christian angelology as an angel of the second highest order of the ninefold celestial hierarchy. Cherubim are mentioned throughout the Hebrew Bible and once in the New Testament in reference to the mercy seat of the Ark of the Covenant (Hebrews 9:5).