Al-Tabari said in his history book citing Abu Makhnaf and Abdullah bin Asim that Al-Dhahak bin Abdullah al-Mashreqi said "I saw the companions of Al-Imam Al-Hussein and his household "peace be upon them" had been killed or badly wounded and there wasn’t anyone left with the Imam but Suwaid bin Amr bin abi Al-Muta'a and Bashir bin Omar Al-Hadhrami (may Allah be pleased with them).(1)
His martyrdom:
After Al-Imam Al-Hussein "pbuh" prayed the noon prayer with what left of his companions and relatives, Al-Hadhrami had come to the Imam in the afternoon for permission to fight, after that, he kept fighting the Yazid's army until he fell as a martyr. (2)
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Sources:
1. Al-Tabari History.
2. The Descent of the Pure Companions.