Musnad Ahmad 908:6

Muhammad ibn Ubayd narrated to us, Ismail narrated to us, from Qays, from Khabbab, who said: We came to the Messenger of Allah, peace and blessings of Allah be upon him, while he was in the shade of the Kaaba, using a cloak of his as a pillow. We said: "O Messenger of Allah, supplicate to Allah for us, and seek victory for us." He said—and his color turned red or changed—: "There were those before you for whom a pit would be dug, and a saw would be brought and placed upon his head, and he would be split in two, yet that would not turn him away from his religion. And he would be combed with iron combs, stripping away the flesh or sinew from the bone, yet that would not turn him away from his religion. Allah will surely complete this matter, until a traveler journeys from Sana'a to Hadramaut, fearing nothing but Allah and the wolf for his sheep. But you are impatient."