The Young Man of Makkah
Muṣʿab ibn ʿUmayr was of the clan of ʿAbd al-Dār, the most indulged young man in Makkah — the sources say his mother clothed him in the finest garments in the city, that he wore Ḥaḍramī sandals, and that people knew where he had been by the scent left behind him.1
He accepted Islam early and secretly at the house of al-Arqam. When his family found out, they imprisoned him. He escaped to Abyssinia with the emigrants and returned; and the Companions who saw him afterwards, in a patched cloak, said they could not look at him without their eyes filling — remembering what he had been.12
Sent to Madīnah
After the first pledge at ʿAqabah, the twelve men of Yathrib asked the Prophet ﷺ to send someone back with them to teach them. He sent Muṣʿab — a young man, alone, into a city he had never seen, split between two tribes that had been at war for generations. He is called for this awwal safīr fī al-Islām, the first ambassador of Islam.3
The best-known scene of that mission has him teaching a group in a garden when Usayd ibn Ḥuḍayr, a chief of al-Aws, came at him with a spear and told him to leave. Muṣʿab said: “Will you not sit and listen? If you like what you hear, accept it; if you dislike it, we will leave you alone.” Usayd sat, listened, and accepted Islam. He then sent Saʿd ibn Muʿādh, the chief of his clan, who came in the same temper and left a Muslim — and Saʿd went straight to his people and told them that speaking to their men and women was forbidden to him until they believed. “By evening,” the report says, “there was not a man or woman among Banū ʿAbd al-Ashhal but was a Muslim.”3
When the Prophet ﷺ arrived in Madīnah the following year, Muṣʿab had brought most of the city with him. Ibn Isḥāq's judgement is that there was hardly a house of the Anṣār without Muslims in it.3
Uḥud
He carried the Muslim banner at Badr and again at Uḥud. When the line broke and the Makkan cavalry came round behind, he stood over the Prophet ﷺ and was killed — struck on the right hand, taking the banner in his left, struck on the left, and holding it against his chest with his stumps until he fell.4
There was nothing to bury him in but a single cloak too short to cover him: when they drew it over his head his feet showed, and when they covered his feet his head showed. The Prophet ﷺ told them to cover his head with it and put grass over his feet.5
Khabbāb ibn al-Aratt, narrating it, added the sentence that later generations remembered the episode by: “Some of us died and left nothing behind, and Muṣʿab ibn ʿUmayr was one of them… and some of us have had their fruits ripen and they are gathering them.”5