The Spelling of "Cherubim" (Cherubs) in Greek (Hebrews 9:5)

Nestle 1904 GNT: Χερουβεὶν

SBL GNT: Χερουβὶν

THGNT: Χερουβὶν

Bill Mounce: "also spelled Χερουβειν and Χερουβιμ, indecl. cherub, a two-winged figure over the ark of the covenant, Heb. 9:5*"

Whatever spelling we prefer, the noun's morphology in Heb. 9:5 is nominative plural neuter.

Compare Exodus 25:18-19; 2 Chronicles 3:11-14.