I said in mine heart, Go to now, I will prove thee with mirth, therefore enjoy pleasure: and, behold, this also is vanity.

I said in my heart: I will go, and abound with delights, and enjoy good things. And I saw that this also was vanity.

I said in my heart, Come now, I will try thee with mirth, therefore enjoy pleasure. But behold, this also is vanity.

I said in my heart, 'Pray, come, I try thee with mirth, and look thou on gladness;' and lo, even it is vanity.

I said in my heart, I will give you joy for a test; so take your pleasure--but it was to no purpose.

I said in my heart: "I will go forth and overflow with delights, and I will enjoy good things." And I saw that this, too, is emptiness.

Solomon's trial of God's second gift, namely, riches, and the enjoyment which riches supply; this brought him to the sane result (compare Ecclesiastes 1:12).
Comparing Solomon's action with Luke 12:16-21, it must be remembered that Solomon's object was the acquisition of wisdom, not self-indulgence, and that he did not fail to look forward to the certainty of death overtaking him.

I will prove thee with mirth - This is well expressed by the author so often referred to. Having tried speculative knowledge in vain, passion and appetite whisper: -
"From the rugged thorny road
Of wisdom, which so ill repays thy toil,
Turn back, and enter pleasure's flowery paths.
Go, take thy fill of joy, to passion give
The reins; nor let one serious thought restrain
What youth and affluence prompt."

I said in my heart, Come now, I will tempt (a) thee with mirth, therefore enjoy pleasure: and, behold, this also [is] vanity.
(a) Solomon makes this discourse with himself, as though he would try whether there was contentment in ease and pleasures.

I said in mine heart,.... He communed with his heart, he thought and reasoned within himself, and came to this resolution in his own mind; that since he could not find happiness in natural wisdom and knowledge, he would seek for it elsewhere, even in pleasure; in which, he observed, some men placed their happiness; or, however, sought for it there: or, "I said to my heart", as the Syriac version;
Go to now; or, "go, I pray thee" (u) listen to what I am about to say, and pursue the track I shall now point out to thee;
I will prove thee with mirth; with those things which will cause mirth, joy, and pleasure; and try whether any happiness can be enjoyed this way, since it could not be had in wisdom and knowledge. Jarchi and Aben Ezra render it, "I will mingle", wine with water, or with spices; or, "I will pour out", wine in plenty to drink of, "with joy", and to promote mirth: but the Targum, Septuagint, Syriac, and Arabic versions, interpret it as we do, and which sense Aben Ezra makes mention of;
therefore enjoy pleasure; which man is naturally a lover of; he was so in his state of innocency, and this was the bait that was laid for him, and by which he was drawn into sin; and now he loves, lives in, and serves sinful pleasures; which are rather imaginary than real, and last but for a season, and end in bitterness: but such sordid lusts and pleasures are not here meant; Solomon was too wise and good a man to give into these, as the "summum bonum"; or ever to think there could be any happiness in them, or even to make a trial of them for that purpose: not criminal pleasures, or an impure, sottish, and epicurean life, are here intended; but manly, rational, and lawful pleasures, for no other are mentioned in the detail of particulars following; and, in the pursuit of the whole, he was guided and governed by his wisdom, and that remained in him, Ecclesiastes 2:3. It may be rendered, "therefore see good" (w); look upon all the good, pleasant, and delectable things of life; and enjoy them in such a manner as, if possible, happiness may be attained in them;
and, behold, this also is vanity; it will be found, by making the experiment, that there is no solid and substantial happiness in it, as it was by himself.
(u) "age, quaeso", Tigurine version, Vatablus, Rambachius. (w) "et vide in bonum", Montanus; "et vide bonum", Vatablus, Mercerus, Cocceius, Gejerus; "fraere bono", Junius & Tremellius, Piscator, Drusius, Amama, Rambachius.

Solomon soon found mirth and pleasure to be vanity. What does noisy, flashy mirth towards making a man happy? The manifold devices of men's hearts, to get satisfaction from the world, and their changing from one thing to another, are like the restlessness of a man in a fever. Perceiving it was folly to give himself to wine, he next tried the costly amusements of princes. The poor, when they read such a description, are ready to feel discontent. But the remedy against all such feelings is in the estimate of it all by the owner himself. All was vanity and vexation of spirit: and the same things would yield the same result to us, as to Solomon. Having food and raiment, let us therewith be content. His wisdom remained with him; a strong understanding, with great human knowledge. But every earthly pleasure, when unconnected with better blessings, leaves the mind as eager and unsatisfied as before. Happiness arises not from the situation in which we are placed. It is only through Jesus Christ that final blessedness can be attained.

(Ecclesiastes. 2:1-26)
I said . . . heart-- (Luke 12:19).
thee--my heart, I will test whether thou canst find that solid good in pleasure which was not in "worldly wisdom." But this also proves to be "vanity" (Isaiah 50:11).

"I have said in mine heart: Up then, I will prove thee with mirth, and enjoy thou the good! And, lo, this also is vain." Speaking in the heart is not here merely, as at Ecclesiastes 1:16-17, speaking to the heart, but the words are formed into a direct address of the heart. The Targ. and Midrash obliterate this by interpreting as if the word were אנסּנּה, "I will try it" (Ecclesiastes 7:23). Jerome also, in rendering by vadam et affluam deliciis et fruar bonis, proceeds contrary to the usual reading of 'אן Niph. of נסך, vid., at Psalm 2:6), as if this could mean, "I will pour over myself." It is an address of the heart, and ב is, as at 1-Kings 10:1, that of the means: I will try thee with mirth, to see whether thy hunger after satisfaction can be appeased with mirth. וּראה also is an address; Grtz sees here, contrary to the Gramm., an infin. continuing the בּשׂ; ūrēh, Job 10:15, is the connect. form of the particip. adj. rāěh; and if reēh could be the inf. after the forms naqqēh, hinnāqqēh, it would be the inf. absol., instead of which וּראות was to be expected. It is the imper.: See good, sinking thyself therein, i.e., enjoy a cheerful life. Elsewhere the author connects ראה less significantly with the accus. - obj., Ecclesiastes 5:17; Ecclesiastes 6:6; Ecclesiastes 2:24.
This was his intention; but this experiment also to find out the summum bonum proves itself a failure: he found a life of pleasure to be a hollow life; that also, viz., devotedness to mirth, was to him manifestly vanity.

I said - Being disappointed of my hopes from knowledge, I resolved to try another course. Go to - O my soul! I will try whether I cannot make thee happy, by the enjoyment of sensual delights. Vanity - Is vain, and unable to make men happy.