Deuteronomy 14:28

Context14:28 At the end of every three years you must bring all the tithe of your produce, in that very year, and you must store it up in your villages.
Deuteronomy 19:15
Context19:15 A single witness may not testify 1 against another person for any trespass or sin that he commits. A matter may be legally established 2 only on the testimony of two or three witnesses.