Neither have I suffered my mouth - Margin, as in Hebrew, palate. The word is often used for the mouth in general, and especially as the organ of the voice from the use and importance of the palate in speaking. Proverbs 8:7. "For my palate (חכי chikiy) speaketh truth." It is used as the organ of taste, Job 12:11; compare Job 6:30; Psalm 119:103.
By wishing a curse to his soul - It must have been an extraordinary degree of piety which would permit a man to say this with truth, that he had never harbored a wish of injury to an enemy. Few are the people, probably, even now, who could say this, and who are enabled to keep their minds free from every wish that calamities and woes may overtake those who are seeking their hurt. Yet this is the nature of true religion. It controls the heart, represses the angry and revengeful feelings, and creates in the soul an earnest desire for the happiness even of those who injure us.

Neither have I suffered my mouth to sin - I have neither spoken evil of him, nor wished evil to him. How few of those called Christians can speak thus concerning their enemies; or those who have done them any mischief!

Neither have I suffered my mouth to sin,.... Which, as it is the instrument of speech, is often the means of much sin; particularly of cursing men, and expressing much bitterness against enemies; but Job laid an embargo upon it, kept it as with a bridle, restrained it from uttering any evil, or wishing any to his worst adversaries; which is difficult to do, when provocations are given, as follows:
by wishing a curse to his soul; not to his soul as distinct from his body, being the superior excellency and immortal part; that it be everlastingly damned, as wicked men wish to their own souls, and the souls of others, but to his person, wishing some calamity might befall him, some disease seize upon him, or that God would take him away by death: Job would never suffer himself to wish anything of this kind unto his enemy.

mouth--literally, "palate." (See on Job 6:30).
wishing--literally, "so as to demand his (my enemy's) soul," that is, "life by a curse." This verse parenthetically confirms Job 31:30. Job in the patriarchal age of the promise, anterior to the law, realizes the Gospel spirit, which was the end of the law (compare Leviticus 19:18; Deuteronomy 23:6, with Matthew 5:43-44).