פירוש על קידושין 48:7

This baraita contains a dispute over whether the slave being emancipated because his master put out his eye, tooth or other major limb, needs a deed of emancipation. The number of sages who participate is somewhat unusual. In the end, a compromise seems to have been reached. Since tooth and eye are mentioned explicitly in the Torah, the slave does not need a deed of emancipation. But for the other limbs, which are only derived through a midrash, he does.