He that despised Moses’ law died without mercy under two or three witnesses:
Berean Study Bible (BSB) - Hebrews 10:28 >Anyone who rejected the law of Moses died without mercy on the testimony of two or three witnesses.
Textus Receptus (TR) - Hebrews 10:28 >Ἀθετήσας τις νόμον Μωσέως χωρὶς οἰκτιρμῶν ἐπὶ δυσὶν ἢ τρισὶ μάρτυσιν ἀποθνῄσκει·