Do not accept testimony from a lone witness

"A single witness shall not rise up against a man on account of any iniquity or any sin which he has committed; on the evidence of two or three witnesses a matter shall be confirmed.

Hebrew

טו לֹא-יָקוּם עֵד אֶחָד בְּאִישׁ, לְכָל-עָו‍ֹן וּלְכָל-חַטָּאת, בְּכָל-חֵטְא, אֲשֶׁר יֶחֱטָא: עַל-פִּי שְׁנֵי עֵדִים, אוֹ עַל-פִּי שְׁלֹשָׁה-עֵדִים--יָקוּם דָּבָר.

Greek

15 Οὐκ ἐμμενεῖ μάρτυς εἷς μαρτυρῆσαι κατὰ ἀνθρώπου κατὰ πᾶσαν ἀδικίαν καὶ κατὰ πᾶν ἁμάρτημα καὶ κατὰ πᾶσαν ἁμαρτίαν, ἣν ἂν ἁμάρτῃ· ἐπὶ στόματος δύο μαρτύρων καὶ ἐπὶ στόματος τριῶν μαρτύρων σταθήσεται πᾶν ῥῆμα.

• Parashah: Shoftim
• Sefer HaChinuch: 523
• Mishneh Torah: Judges — Testimony

• Deuteronomy 19:15

Enumeration and classification from BibleData. The Greek is the Septuagint reading of the same verse, carried by the source for comparison.