Contradiction with Exodus 20:7
Encourages keeping oaths, while some may interpret specific vows differently.
Exodus 20:7: Thou shalt not take the name of the LORD thy God in vain; for the LORD will not hold him guiltless that taketh his name in vain.
Contradiction with Matthew 5:34
Advises against swearing oaths, contradicting the notion of making vows as in Psalms 56:12.
Matthew 5:34: But I say unto you, Swear not at all; neither by heaven; for it is God's throne:
Contradiction with James 5:12
Tells believers not to swear by any oath, which contrasts with the commitment to vows in Psalms 56:12.
James 5:12: But above all things, my brethren, swear not, neither by heaven, neither by the earth, neither by any other oath: but let your yea be yea; and [your] nay, nay; lest ye fall into condemnation.