Midrash su Salmi 127:5

Our Rabbis were taught that the Scripture consists of four thousand, eight hundred and eighty-eight passages. Psalms contain eight passages more than Scriptures; Chronicles has eight less. Our Rabbis taught (Deut. 4, 7) V'shinantam (And thou shall teach them diligently), this means that the Torah shall be so clear in your mouth, so that when one will ask you a thing you should not stammer but answer him directly; (Ib. b) as it is said (Pr. 7, 4) Say unto wisdom thou art my sister, etc.; and there is a preceding passage, Bind them around thy fingers, inscribe them upon the tables of thy heart; and there is another passage (Ps. 127, 4) Like arrows in the hand of a mighty man so are the children of youth. Again there is another passage (Ib. 45, 6) Thy sharpened arrows, and again there is another passage (Ps. 127, 5) Happy is the man that hath his quiver full of them; they shall not be put to shame, when they speak with their enemies in the gate. Said R. Chiya b. Abba: "Even a father and his son, a teacher and his disciple who study the Torah in one place become enemies to each otlier [as a result of Halachik discussion]. However, they do not leave the place until they are reconciled again, as it is said (Num. 21, 14) Vaheb in Suffa. Do not read Suffa, but Soffa (at the end)."