Musannaf Ibn Abi Shaybah

Hazrat Mujahid says that in the beginning, there were seven people who openly declared Islam: the Messenger of Allah (peace and blessings be upon him), Hazrat Abu Bakr, Hazrat Bilal, Hazrat Khabbab, Hazrat Suhaib, Hazrat Ammar, and Umm Ammar Hazrat Sumayyah. The Messenger of Allah (peace and blessings be upon him) was protected from the disbelievers by his uncle, and Hazrat Abu Bakr was protected by his tribe from the disbelievers, but the others were seized and made to wear iron shirts. Then the disbelievers left them to burn in the sun. When their suffering reached its peak, they pleaded, and their plea was granted. Then the tribe of each man who had water came to him and put him in it, then took him away from its sides, except for Hazrat Bilal. When night fell, Abu Jahl came and began to abuse Hazrat Sumayyah, then Abu Jahl struck her with a spear and killed her. Thus, she was the first woman to be martyred in Islam. So Hazrat Bilal considered his life insignificant for the sake of Allah, until the polytheists became desperate and put a rope around his neck. Then the polytheists ordered their children, and they began to drag Hazrat Bilal between the mountains of Mecca. And Hazrat Bilal began to say, "Ahad, Ahad" (One, One).