One of the extremely significant steps undertaken by the Holy Prophet (s.a.w), five or eight months after his migration to Madinah, was to establish the bond of brotherhood between the Muhaajir (The Emigrants) and the Ansaar (The Helpers).
A’bdullah Ibn A’bbas says:
When the verse
اِنَّماَ الْمُؤمِنُونَ اِخْوَةٌ
(The believers are but brethren) was revealed, the Holy Prophet (s.a.w.) proclaimed brotherhood to be a general law amongst the Muslims and, taking into consideration their ranks and positions, established the bond between every two persons by making one the brother of the other; Abu Bakr with U’mar, U’thman with A’bd al-Rahmaan and so on.
Amirul Mu’mineen (a.s.) had stretched himself on the ground, when the Holy Prophet (s.a.w.) approached him and said:
“Arise, O’ Abu Turaab! By God! I have not made you the brother of anyone for I have kept you for myself.”( Namunah-e-Ma’arif, vol. 1, pg. 82; Kashf al-Ghummah; Tafseer al-Burhaan.)