If your name is Mus'ab, you're named after Mus'ab ibn Umayr.
Before the Prophet ﷺ ever arrived in Medina, Mus'ab was already there. A companion from Medina, al-Bara ibn Azib, said: "The first of them to come to us were Mus'ab ibn Umayr and Ibn Umm Maktum, and they were teaching people the Quran." (Sahih al-Bukhari 3925)
Another companion, Khabbab, remembered him:
"We emigrated with the Prophet ﷺ for the sake of Allah, so our reward was with Allah. Some of us died without taking anything of their reward in this world, and Mus'ab ibn Umayr was one of them. He was martyred at Uhud, and all we could find to shroud him in was one cloak. When we covered his head, his feet showed. When we covered his feet, his head showed. So the Prophet ﷺ told us to cover his head and put idhkhir grass over his feet." (Sahih al-Bukhari 1276)
He took nothing from this world. His whole reward was still waiting for him.
