The Messenger of Allah supported the oppressed
According to the terms of the Hudaybiyah peace treaty, everyone had the choice to enter into an alliance and pay allegiance to either the Messenger of Allah, sallallaahu `alayhi wa sallam ( may Allah exalt his mention ), or the Quraysh.
As a consequence, Banu Bakr paid allegiance to Quraysh, and Khuza‘ah paid allegiance to the Prophet, sallallaahu `alayhi wa sallam ( may Allah exalt his mention ). There were wars between Banu Bakr and Khuza‘ah during the pre-Islamic era, and during the treaty between them, Nawfal Ibn Mu‘awiyah, from Banu Bakr, led a group of men from his people and headed to the tribe of Khuza‘ah. They reached Khuza‘ah at night and killed a man called Munabbih. Thereupon, the people of Khuza‘ah woke up and started fighting them. Quraysh provided Banu Bakr with weapons and some of them fought with Banu Bakr at night. When the war ended, ‘Amr Ibn Salim may Allah be pleased with him went to the Prophet, sallallaahu `alayhi wa sallam ( may Allah exalt his mention ), and when he reached him, while he was sitting in the Masjid, he said some poetic verses describing the attack and the breaching of the treaty. He sought the support of the Prophet, sallallaahu `alayhi wa sallam ( may Allah exalt his mention ). Ibn Ishaq may Allah have mercy upon him said, “The Messenger of Allah said to him: ‘O ‘Amr Ibn Salim, you are supported.’ This was the cause of the conquest of Makkah.” [Fat’h Al-Bari 592/7]

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