“For.” The standard meaning of the Hebrew word is “for.” Tremper Longman explains that the “for” likely connects to the last phrase in Ecclesiastes 7:6, that “this too is pointless.” Longman writes, “The wise are not above suspicion. There are factors as to why their advice and/or rebuke may not be reliable” (The New International Commentary on the Old Testament: Ecclesiastes). In spite of the very possible connection between 7:6 and 7:7, most translators agree with the explanation given by James Bollhagen (Concordia Commentary: Ecclesiastes): “The opening כִּיis usually interpreted as an asseverative [a positive affirmation], the intensifier “indeed,” as in Ecc. 4:16 and 7:20.” However, Longman’s advice is to translate the text as it stands, “for” and that seems correct.
There is no real reason to doubt the connection between Ecclesiastes 7:6 and 7:7, especially in light of the whole flow of Ecclesiastes, which up to this point (and continuing forward for most of the book) has a decidedly cynical view (some might say “a very honest view”) of this earthly life and what goes on in it. It would be nice if the rich and powerful were always honest and wise, but far too often the “wise decisions” that they make are based on ulterior motives and pressures from behind-the-scenes players.
“extortion.” The translation “extortion” (getting something, often money, through force or threats) is a good one, and here it also would include various ways of extorting money or favors, including blackmail. The rich and powerful, usually considered “wise,” are subject to extortion, and the last phrase in the verse mentions bribery, which was so common that the Mosaic Law mentions bribes several times (cp. Exod. 23:8; Deut. 16:19; 27:25. Deut. 10:17 says the God will not take a bribe).
“makes the wise man foolish.” The Hebrew verb means to make foolish (HALOT Hebrew-English lexicon). Although there are some scholars who think word relates to being “mad,” the lexical and contextual evidence supports “fool” being the correct meaning of the Hebrew text.
Ecclesiastes 7:7 adds questionable motives and therefore questionable quality to the advice of the wise. It points out what often happens to the rich and powerful people who are supposedly wise and give wise advice: they succumb to extortion and bribery. By giving in to evil, through pressure or because of their own greed and aspirations, the “wise” person becomes a “fool.” This life is short—very short—and eternity is a very long time. The person who trades everlasting life and/or future rewards for material gain in this life is indeed a fool.
The fact that the “wise” people give in so often to evil forces that pervert their judgment and advice adds to the seeming pointlessness of this life. But it also forces people to a point of decision: we can be cynical about this life because so much of it seems wrong and unfair, or we can be positive about this life, realizing that it is a war zone between good and evil and we can support God and good in this life and look forward to a wonderful next life as well. The Devil is the god of this age, and God is a man of war (Exod. 15:3) fighting against him, and we can be cynics and negative and inadvertently give aide to the Devil, or we can have a positive point of view and spread the good word about our loving God and the wonderful next life He will provide.
“destroys the heart.” In biblical Hebrew, the “heart” can be the mind or understanding, or as it does here, it can have the wider meaning of the center of one’s life and personality (see commentary on Prov. 15:21). The heart is always changing, and it can change for the better or for the worse. The hearts of people who refuse to acknowledge God grow “dark” (Rom. 1:21). People who participate in evil spiral downhill. Their hearts become harder and harder and their lives become more and more ungodly (Eph. 4:18-19).