Hadhrat Anas Radiallahu Anhu says that on one occasion the Aws and Khazraj tribes boasted to each other. The Aws said, “Amongst us was the person whom the angels bathed (after his martyrdom). He was Handhala bin Raahib Radiallahu Anhu. Also amongst us was the person for whom the throne of Allaah shook (when he passed away). He was Sa’d bin Mu’aadh Radiallahu Anhu.
Amongst us was also the person who was protected by a swarm of wasps (when the Mushrikeen intended to mutilate his body). He was Aasim bin Thaabit bin Abil Mah Radiallahu Anhu. We also had in our ranks the person whose testimony was allowed (by Rasulullah Sallallahu Alayhi Wasallam) in place of the testimony of two people. He was Khuzayma bin Thaabit Radiallahu Anhu. May Allaah be pleased with all of them.”
In response to this, the members of the Khazraj said, ‘We have four persons who memorised the entire Qur’aan during the lifetime of Rasulullah Sallallahu Alayhi Wasallam.
There were none besides them who achieved this honour. They were Zaid bin Thaabit Radiallahu Anhu, Ubay bin Ka’b Radiallahu Anhu, Mu’aadh bin Jabal Radiallahu Anhu and Abu Zaid Radiallahu Anhu. May Allaah be pleased with all of them.”