וְאִם־שֵׁ֥ן עַבְדּ֛וֹ אֽוֹ־שֵׁ֥ן אֲמָת֖וֹ יַפִּ֑יל לַֽחָפְשִׁ֥י יְשַׁלְּחֶ֖נּוּ תַּ֥חַת שִׁנּֽוֹ׃ (פ)
And if he smite out his bondman’s tooth, or his bondwoman’s tooth, he shall let him go free for his tooth’s sake.
Read kabbalistic (mystical) interpretation of Exodus 21:27: and classical mystical sources.