Counting the Two Armies

The Messenger of Allah (peace be upon him) asked him about how much meat they were consuming daily, and from that would know the number of the army — he said they would be between nine hundred and a thousand, and they were nine hundred and fifty. The army was nine hundred and fifty strong, the cavalry was two hundred strong, they had six hundred coats of mail, and they had slave girls for entertainment, while the Muslim army was a little over three hundred — a third of the number of the army of Quraysh. The Muhājirūn numbered eighty-six, the Aws were sixty-one, and the Khazraj were a hundred and seventy. The reason the Aws were fewer than the Khazraj, sixty-one to a hundred and seventy, even though they were as strong and as brave and as numerous as the Khazraj, is that the dwellings of the Aws were in the upper part of Madīnah, and the Messenger of Allah (peace be upon him), when he mobilised this army, said that they should only join if they had their camel ready, their ride ready, and because the Aws were a bit farther away, they were not able to join in this army in the same numbers as the Khazraj.

Al-Barāʾ ibn ʿĀzib (may Allah be pleased with him) said, "We, the Companions of the Messenger of Allah (peace be upon him), when we would talk about the Battle of Badr, we would say that the number of the people who participated in the Battle of Badr is equal to the number of the people who participated with Ṭālūt after they had crossed the river with him, and only a believer crossed with him" — a little over three hundred and ten (Ṣaḥīḥ al-Bukhārī, no. 3957). The correlation between the number of the Muslims at the Battle of Badr and the number of the companions who crossed with Ṭālūt, and the fact that only those who passed the trial of the river joined him, tells that the believers who were at the Battle of Badr were also the best — those who had passed the trials of this world. The exact number, some give as three hundred and seventeen, some give as three hundred and nineteen; it is close to this range.