The idolators suffered many casualties among their noble men at the battle of Badr. The caravan that Abu Sufyan led (before Badr) returned safely to Makkah, prompting the remaining Makkan leaders and the children of those who were killed at Badr to demand from Abu Sufyan to, “Spend this money on fighting Muhammad!” Consequently, they spent the money from the caravan on warfare expenses and mobilized their forces including the Ahabish tribes (tribes living around the city). They gathered three thousand soldiers and marched until they camped near Uhud facing Al-Madinah. The Messenger of Allah led the Friday prayer and when he finished with it, he performed the funeral prayer for a man from Bani An-Najjar called Malik bin `Amr. The Prophet then asked the Muslims for advice, if they should march to meet the disbelievers, or fortify themselves in Al-Madinah. `Abdullah bin Ubayy (the chief hypocrite) advised that they should remain in Al-Madinah, saying that if the disbelievers lay siege to Al-Madinah, the siege would be greatly disadvantageous to them. He added that if they decide to attack Al-Madinah, its men would face off with them, while women and children could throw rocks at them from above their heads; and if they decide to return to Makkah, they would return with failure. However, some companions who did not attend the battle of Badr advised that the Muslims should go out to Uhud to meet the disbelievers.
The Messenger of Allah went to his home, put on his shield and came out. The companions were weary then and said to each other, “Did we compel the Messenger of Allah to go out” They said, “O Messenger of Allah! If you wish, we will remain in Al-Madinah. ” The Messenger of Allah said,
«مَا يَنْبَغِي لِنَبِيَ إِذَا لَبِسَ لَأْمَتَهُ أَنْ يَرْجِعَ حَتَّى يَحْكُمَ اللهُ لَه»
(It is not for a Prophet to wear his shield for war then lay down his arms before Allah decides in his favor.)
The Messenger of Allah marched with a thousand of his Companions. When they reached the Shawt area, `Abdullah bin Ubayy went back to Al-Madinah with a third of the army, claiming he was angry the Prophet did not listen to his advice. He and his supporters said, “If we knew that you would fight today, we would have accompanied you. However, we do not think that you will fight today.” The Messenger of Allah marched until he reached the hillside in the area of Uhud, where they camped in the valley with Mount Uhud behind them. The Messenger of Allah said,
«لَا يُقَاتِلَنَّ أَحَدٌ حَتَّى نَأْمُرَهُ بِالْقِتَال»
(No one starts fighting until I issue the command to fight.)
The Messenger prepared his forces for battle, and his army was seven hundred men. He appointed `Abdullah bin Jubayr, from Bani `Amr bin `Awf, to lead the archers who were fifty men. The Prophet said to them,
«انْضَحُوا الْخَيْلَ عَنَّا، وَلَا نُؤْتَيَنَّ مِنْ قِبَلِكُمْ، وَالْزَمُوا مَكَانَكُمْ، إِنْ كَانَتِ النَّوْبَةُ لَنَا أَوْ عَلَيْنَا، وَإِنْ رَأَيْتُمُونَا تَخْطَفُنَا الطَّيْرُ فَلَا تَبْرَحُوا مَكَانَكُم»
(Keep the horsemen away from us, and be aware that we might be attacked from your direction. If victory was for or against us, remain in your positions. And even if you see us being picked up by birds, do not abandon your positions.)
The Prophet wore two protective shields and gave the flag to Mus`ab bin `Umayr of Bani `Abd Ad-Dar. The Prophet also allowed some young men to participate in fighting, but not others, whom he allowed to participate in the battle of Al-Khandaq two years later. The Quraysh mobilized their forces of three thousand men with two hundred horsemen on each flank. They appointed Khalid bin Al-Walid to lead the right side of the horsemen and `Ikrimah Ibn Abi Jahl on the left side. They also gave their grand flag to the tribe of Bani `Abd Ad-Dar. Allah willing, we will mention the details of this battle later on, if Allah wills. Allah said here,
﴿وَإِذْ غَدَوْتَ مِنْ أَهْلِكَ تُبَوِّىءُ الْمُؤْمِنِينَ مَقَاعِدَ لِلْقِتَالِ﴾
(And (remember) when you left your household in the morning to post the believers at their stations for the battle) ﴿3:121﴾, designating them to various positions, dividing the army to the left and right sides and placing them wherever you command them.
﴿وَاللَّهُ سَمِيعٌ عَلِيمٌ﴾
(And Allah is All-Hearer, All-Knower), He hears what you say and knows what you conceal in your hearts. Allah said next,
﴿إِذْ هَمَّتْ طَّآئِفَتَانِ مِنكُمْ أَن تَفْشَلاَ﴾
(When two parties from among you were about to lose heart,) ﴿3:122﴾.
Al-Bukhari recorded that Jabir bin `Abdullah said, “The Ayah,
﴿إِذْ هَمَّتْ طَّآئِفَتَانِ مِنكُمْ أَن تَفْشَلاَ﴾
(When two parties from among you were about to lose heart) was revealed about us, ﴿the two Muslim tribes of﴾ Bani Harithah and Bani Salamah. I (or we) would not be pleased if it was not revealed, because Allah said in it,
﴿وَاللَّهُ وَلِيُّهُمَا﴾
(but Allah was their Wali (Supporter and Protector)) ﴿3:122﴾.”
Muslim recorded this Hadith from Sufyan bin `Uyaynah.
Credit:.Tafsir Ibn Kathir
