Deuteronomy 17:6 is the OT law requiring two witnesses for a death sentence, which Jesus directly references here to establish the principle of valid testimony.

Deuteronomy 19:15 states the same two-witness requirement for any charge, the legal basis Jesus cites here for the truth of his testimony.

Matthew 18:16 applies the same two-witness principle to church discipline — establishing truth through witnesses.

2 Corinthians 13:1 quotes the same principle for judgment — every matter established by two or three witnesses.

Hebrews 10:28 recalls the OT law requiring two witnesses for capital punishment — the same law Jesus references.

Numbers 35:30 is the OT law itself requiring two witnesses for murder — the source of the principle Jesus cites.

1 Timothy 5:19 applies the two-witness rule to accusations against elders — a direct parallel in church discipline.