“Rabbi Elazar said, ‘Why is it written, ‘She opened her mouth with wisdom and the Torah [law] of mercy was on her tongue’? There is Torah of mercy and there is Torah that is not of mercy. Torah Lishma [for Her sake] is Torah of mercy. Lo Lishma [not for Her sake] is Torah that is not of mercy. That is, Torah in order to bestow is called mercy, the quality of Hassadim [mercies].’”
“It is said, ‘Torah to teach is Torah of mercy; not to teach is Torah that is not of mercy” (Sukkah 49).
We should understand why if he does not teach others, it is regarded as not being of mercy. It is possible that the meaning of “to teach” refers to its own body and not simply teaching, meaning that he teaches the body to do everything in order to bestow, and this is why it is called “Torah of mercy.” This change of phrasing, each one interprets the intention of the verse differently.