Eccl 12:8-12 – (8) Vanity of vanities, saith the preacher; all is vanity. (9) And moreover, because the preacher was wise, he still taught the people knowledge; yea, he gave good heed, and sought out, and set in order many proverbs. (10) The preacher sought to find out acceptable words: and that which was written was upright, even words of truth. (11) The words of the wise are as goads, and as nails fastened by the masters of assemblies, which are given from one shepherd. (12) And further, by these, my son, be admonished: of making many books there is no end; and much study is a weariness of the flesh.
For the SIH devotional on this subject: