Reference for Kiddushin 48:12
ת"ר הכהו על עינו וכהתה על שינו ונדדה אם יכול להשתמש בהן עכשיו אין עבד יוצא בהן לחירות ואם לאו עבד יוצא בהן לחירות תניא אידך הרי שהיתה עינו כהויה וסמאה שינו נדודה והפילה אם יכול להשתמש בהן כבר עבד יוצא בהן לחירות ואם לאו אין עבד יוצא בהן לחירות
since, however, it is written: 'to freedom shall he send him away', it implies that he is free at the very outset.<span class="x" onmousemove="('comment',' I.e., as soon as he is assaulted he automatically becomes free, and hence no deed is required. - Now, this can apply only to the loss of his eye or tooth, which are distinctly stated in that verse. But the other limbs are included only because 'he shall send him away' is an extension (v. supra) ; hence in respect of those, R. Simeon's exegesis, assimilating the freedom of a slave to that of a woman, may still hold good. Therefore those who compromised ruled that a deed is unnecessary when he loses his eye or tooth, but is necessary in all other cases (Riba in Tosaf.) .');"><sup>22</sup></span> Our Rabbis taught: If he smites his eye and blinds it, [or] his ear, and deafens it, the slave goes out [to freedom] on their account; near<span class="x" onmousemove="('comment',' Lit., 'against'.');"><sup>23</sup></span> his eye, so that he cannot see, [or] near his ear, and he can not hear,<span class="x" onmousemove="('comment',' I.e., he forcibly strikes a wall or any other object near his ear, and the shock or noise paralyses his optical or aural nerves, rendering him blind or deaf.');"><sup>24</sup></span>