Deuteronomy 17:6
At the mouth of two witnesses, or three witnesses, shall he that is worthy of death be put to death; but at the mouth of one witness he shall not be put to death.
Cross-reference
Deuteronomy 19:15 repeats the two-witness requirement for any crime, reinforcing the legal principle applied here to capital cases.
Numbers 35:30 applies the same two-witness rule to murder cases, extending the principle from this general legal statute.
Matthew 18:16 applies the two-witness principle to church discipline, directly citing the OT law as authority.
John 8:17 cites the same OT witness law, using it to validate Jesus' own testimony about himself.
John 8:18 demonstrates Jesus' use of the two-witness rule: his own testimony plus the Father's fulfill the legal requirement.
Paul directly cites the two-witness principle from Deuteronomy for confirming facts in church discipline.
Paul applies the same two-witness standard to accusations against elders, echoing the OT judicial rule.
Hebrews references the death penalty on two witnesses from Deuteronomy to contrast with greater judgment for rejecting Christ.