And the evidence that the Prophet, peace and blessings be upon him, only exempted charity from wealth in the case of slaves, and not the charity of al-Fitr.
Abu Huraira (may Allah be pleased with him) reports that the Messenger of Allah (peace be upon him) said: "No charity is obligatory upon a Muslim for his slave and his horse except for the charity of Fitr."
Hadith Referenceصحيح ابن خزيمه / جماع أبواب صدقة المواشي من الإبل والبقر والغنم / 2288