Deuteronomy 23:21-23

Geneva(i) 21 When thou shalt vowe a vowe vnto the Lord thy God, thou shalt not be slacke to paye it: for the Lord thy God will surely require it of thee, and so it should be sinne vnto thee. 22 But when thou absteinest from vowing, it shalbe no sinne vnto thee. 23 That which is gone out of thy lippes, thou shalt keepe and performe, as thou hast vowed it willingly vnto the Lord thy God: for thou hast spoken it with thy mouth.