John Gill Commentary Ecclesiastes 7:22

"for oftentimes also thine own heart knoweth that thou thyself likewise hast cursed others." — Ecclesiastes 7:22 (ASV)

For often also your own heart knows Or "your conscience", as the Vulgate Latin version, which is as a thousand witnesses; which, if a man attends to, he will be convinced of his own faults, failings, and infirmities, he is frequently in the commission of.

Particularly, that you yourself likewise have cursed others; either in heart, or with the tongue; thought ill of them, wished ill to them; spoke contemptibly of them, reviled and reproached them; called them by bad names, and abused them; and said some very hard and severe words concerning them, in a passionate fit, being provoked; and afterwards repented of it, being better informed of the state of the case, or being convinced of the evil of passion and rash speaking; and therefore such should consider the like passions and infirmities of others, and pass over them, and forgive them: so Alshech, "if you have cursed others, and do desire men should forgive you, so do you also forgive;" see (Matthew 6:14Matthew 6:15) .

The word "often", in the first clause, is to be connected, not with the word "knows", as if a man often knew this, but with the word "cursed"; suggesting, that a man may be often guilty of this himself, and therefore should be more sparing of his censures of others; see (Matthew 7:1–5) .