I know that [there is] no good in them,.... In these things; as the Arabic version; in the creatures, as Jarchi; in all sublunary enjoyments; in everything the wise man had made a trial of before, as natural Wisdom and knowledge, worldly pleasure, riches, and wealth; the "summun bonum", or happiness of men, did not lie in these things; this he knew by experience, and had the strongest assurance of it: or in them, that is, the children of men, as the Targum: there is no real good thing in them, nor comes out of them, nor is done by them; they cannot think a good thought, nor do a good action, of themselves.
Or rather the sense is, I know there is nothing better for them than what follows:but for [a man] to rejoice; not in sin and sinful pleasures, in a riotous, voluptuous, and epicurean manner; but to be cheerful, and enjoy the blessings of life in a comfortable way, and with a thankful heart; and especially to rejoice in spiritual things, and above all in Christ; and not in any self-boastings or carnal confidences, all such rejoicing is evil; see Ec 9:7.