The immediate occasion here is the two hostile tribes of AWS and KHAZRAJ who lived in Medina for many decades in hostility and ill will. It was only after the prophet's emigration, that the two rival tribes, left their long enmity and adhered to religious brotherhood; and could leave in peace and friendship. They then obtained the honourable Islamic title of the; `HELPERS OF THE PROPHET - ANSطR'
One of the wonderful miracles of our prophet S.A. was the union and brotherhood produced among the jarring, excitable, fond of war, tribes of AWS and KHAZRAJ:
And Allah put affection between their hearts. Had you expended all that is in the earth, you could not make their hearts so attached together in friendship and brotherhood, but Allah did that easily, and brought their far-away hearts together for, He is All- mighty, All- wise.''