Contradiction with James 1:19
Mark 9:6 describes Peter speaking out of fear and not knowing what to say, while James 1:19 advises being slow to speak, implying thoughtfulness and restraint.
James 1:19: Wherefore, my beloved brethren, let every man be swift to hear, slow to speak, slow to wrath:
Contradiction with Proverbs 17:28
Mark 9:6 shows Peter speaking without understanding, contradicting Proverbs 17:28 which suggests even a fool is considered wise if they remain silent.
Proverbs 17:28: Even a fool, when he holdeth his peace, is counted wise: [and] he that shutteth his lips [is esteemed] a man of understanding.
Contradiction with Proverbs 10:19
Mark 9:6 has Peter speaking without thinking, while Proverbs 10:19 warns that in many words, transgression is not lacking, implying restraint in speech is wise.
Proverbs 10:19: In the multitude of words there wanteth not sin: but he that refraineth his lips [is] wise.
Contradiction with Ecclesiastes 5:2
Mark 9:6 involves Peter speaking impulsively, in contrast to Ecclesiastes 5:2 which advises not to be rash with words, especially before God.
Ecclesiastes 5:2: Be not rash with thy mouth, and let not thine heart be hasty to utter [any] thing before God: for God [is] in heaven, and thou upon earth: therefore let thy words be few. [thing: or, word]