Musannaf Ibn Abi Shaybah 37393 — The words of Salman

And he wrote to him: Knowledge is like springs; Allah benefits by it whomever He wills. The likeness of wisdom that is not spoken is that of a body without a soul. The likeness of knowledge that is not acted upon is that of a treasure from which nothing is spent. And the likeness of the scholar is that of a man for whom a lamp was lit on a road, so the people began to take light from it, and each of them prays for him.