It is narrated from Sayyiduna Salman al-Farisi (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) was asked about ghee, cheese and the meat of the wild ass, and he (peace and blessings be upon him) said: "The lawful is what Allah has made lawful in His Book, and the unlawful is what Allah has made unlawful in His Book, and whatever Allah remained silent about is among the things He has pardoned (that is, made permissible)." This is a sahih (authentic) and clear hadith on this subject; however, the two Shaykhs (Bukhari and Muslim) did not record the narration of Sayf bin Harun.