A.T. Robertson Commentary Hebrews 10:28

"A man that hath set at nought Moses law dieth without compassion on [the word of] two or three witnesses:" — Hebrews 10:28 (ASV)

Hath set at naught (αθετησας). First aorist active participle of αθετεω, late compound, very common in LXX, from alpha privative and τιθημ, to render null and void, to set aside, only here in Hebrews , but note αθετησις (Hebrews 7:18; Hebrews 9:26).

Without mercy (χωρις οικτιρμων). See 2 Corinthians 1:3. This was the law (Deuteronomy 17:6) for apostates.

On the word of two or three (επ δυσιν η τρισιν). "On the basis of two or three." For this use of επ with the locative see 9:17.