Mishnah 13 - Chapter 1 - Pirkei Avot

He (Hillel) was wont to say: One who projects ("negad") his name loses his name. [One who "stretches out" his name (afar) in lordship and authority will soon lose his name, for "lordship buries its practitioners." (The targum of "mishchu" is "negidu.")], and he who does not add [to his learning], there will end (yasif) [from his mouth what he has already learned and he will forget his learning. Others read it "ye'asef (i.e., "he will be gathered in" to his people and he will die before his time.], and he who does not learn [(ab initio, which is more severe than not adding to one's learning,)] incurs the penalty of death. [That is, he deserves to be killed (viz. Pesachim 49b): "It is permitted to rip an ignoramus open, like a fish — and from his back," (such "ripping" being mortal)], and one who "uses" (i.e., exploits) the "crown" (taga) [of Torah (as one who "uses" his dishes)] passes away [from the world. There are some who explain "taga" as "talmid" (disciple); "gavra" (a man); "achrina" (another) — i.e., it is forbidden for a man to employ for his benefit disciples who are not his own. And I have heard: "And one who uses taga (the ineffable Name) passes away and is lost (from the world), not having a share in the world to come.]