Contradiction with Numbers 23:19
This verse states "God is not a man, that he should lie; neither the son of man, that he should repent: hath he said, and shall he not do it? or hath he spoken, and shall he not make it good?" Here, it is emphasized that God does not lie or change His mind, suggesting His promises are based on His word, not necessarily on an oath, contrasting with Hebrews 6:13's emphasis on God swearing by Himself.
Numbers 23:19: God [is] not a man, that he should lie; neither the son of man, that he should repent: hath he said, and shall he not do [it]? or hath he spoken, and shall he not make it good?
Contradiction with Isaiah 45:23
This verse says, "I have sworn by myself, the word is gone out of my mouth in righteousness, and shall not return," indicating that God swears by Himself to declare His word, which aligns more than contradicts. However, the potential contradiction lies in the nuance that God's word itself is binding, not requiring an oath as in Hebrews 6:13.
Isaiah 45:23: I have sworn by myself, the word is gone out of my mouth [in] righteousness, and shall not return, That unto me every knee shall bow, every tongue shall swear.
Contradiction with Matthew 5:34-35
In these verses, Jesus says, "But I say unto you, Swear not at all; neither by heaven; for it is God's throne: Nor by the earth; for it is his footstool," which instructs against swearing oaths at all, presenting a contradiction to the concept in Hebrews 6:13 where God swears by Himself.
Matthew 5:34-35: But I say unto you, Swear not at all; neither by heaven; for it is God's throne:
Contradiction with James 5:12
This verse commands, "But above all things, my brethren, swear not, neither by heaven, neither by the earth, neither by any other oath," which contradicts the practice of swearing oaths, including God swearing by Himself in Hebrews 6:13.
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.