Bond of Brotherhood
The Holy Prophet (sa) established a bond of brotherhood between Hazrat Sa‘d bin Abi Waqas (ra) and Hazrat Mus‘ab bin Umair (ra), whereas according to another narration the bond of brotherhood was established between Hazrat Sa‘d bin Abi Waqas (ra) and Hazrat Sa‘d bin Mu‘az (ra).
(Al-Tabaqaat-ul-Kubra li ibn Sa‘d, Vol. 3, pp. 103, Sa‘d bin Abi Waqas (ra), Dar-ul-Kutub al-Ilmiyyah, Beirut, 1990)
Maulana Ghulam Bari Sahib Saif has presented a justification for the difference between the two narrations. He states that perhaps in Mecca, the bond of brotherhood was established with Hazrat Mus‘ab bin Umair (ra) and in Medina it was established with Hazrat Sa‘d bin Mu‘az.
(Roshan Sitarey az Ghulam Bari Saif Sahib, Vol. 2, p. 64)