Musnad Ahmad 26:504

Sulayman ibn Dawud narrated to us, Zuhayr narrated to us, Abu Ishaq narrated to us, from Abu al-Ahwas, from Abdullah, who said: We came to the Messenger of Allah, may Allah bless him and grant him peace, regarding a man, asking his permission to cauterize him. He remained silent. Then we asked him a second time, and he remained silent. Then we asked him a third time. He said: "Heat stones for him if you wish," as if he were angry.