Qo 12, 11-13
11 The words of the wise are like goads, their collected sayings like firmly embedded nails: given by one shepherd.
12 Be warned, my son, of anything in addition to them. Of making many books there is no end, and much study wearies the body.
13 Now all has been heard; here is the conclusion of the matter: Fear GOD and keep His Commandments, for this is the duty of all mankind.
This Book of the Bible called in Hebrew קֹהֶלֶת (Qoelet or Khoeleth), both of the Hebrew and Christian canon, discusses the meaning of life and the best way to live it. He also proclaims that all human actions are intrinsically הבל (transliterated: Hebel), which means “vain”, “futile”, “meaningless”. This can be affirmed since the fate that unites the opposite destiny: both the wise and the foolish put an end to their life in death, and no one can escape this fate. Qoelet (Kohelet קֹהֶלֶת is the pseudonym attributed to the author) clearly states that Wisdom is the means to best enjoy earthly existence.
These are the verses that close this marvelous Book that the Jewish tradition classifies in the Writings (K’tuvim כְּתוּבִים) while the Christian one in the Sapiential Books. And in fact it is mainly to Sapienza and to the experiences that are referred to.
11 and 12 seem antithetical, but in reality they only try to invite the believer to balance in life. A moderation between the fundamental importance (in v. 11) of learning from the Fathers through oral traditions and writings, and the containment of excessive study that tires the body and the mind (v. 12).
On the other hand, verse 13 hold all the content of the doctrine in a single phrase “Fear GOD and observe His Commandments”, this fear is really the key to an happy life pleasing the believing men and women. This principle is strongly attested by the Qur’an and by the Muslim tradition (see for example chapters: 2, 2 ; 3, 102 ; 3, 175 ; 3, 200 ; 4, 77 ; 4, 131 ; 5, 8 and many others), bringing together the foundations of the Abrahamic Religions.