Surah 8. Al-Anfal, Ayah 7

Lit., "while you would have liked the one which was not powerful to be yours" - i.e., the caravan coming from Syria, which was accompanied by only forty armed men and could, therefore, be attacked without great danger.

The destruction of the Meccan army at Badr was the prelude to the elimination, in the course of the next few years, of all opposition to Islam in its homeland: and it is to this future fulfilment of God's promise that the above words refer. See also surah {11}, note [103].

 After many years of persecution in Mecca, the Prophet (ﷺ) and many of his early followers decided to emigrate secretly to Medina, about 250 miles to the north, leaving behind their homes and valuables, which were soon taken over by the pagans of Mecca. To avenge  this financial loss, the Prophet (ﷺ) decided to capture an unarmed Meccan trade caravan headed by Abu Sufyân, a Meccan chief. Eventually, the caravan escaped, but the Meccans mobilized an army of over 1000 well-armed soldiers, more than three times the size of the Muslim force. Many Muslims had hoped to capture the caravan without having to meet the Meccan army in battle. Although the Muslims were vastly outnumbered and lightly-armed, they still won this decisive battle.

Just before Badr there were two alternatives before the Muslims in Madinah to save themselves from being overwhelmed by the Makkan Quraish with all their resources from the rich Syrian trade. One, which had least danger for the time being, and also promised much booty, was to fall upon the Quraish caravan returning from Syria to Makkah richly laden, and led by Aba Sufyan with only 40 men unarmed. From a wordly point of view this was the safest and most lucrative course. The other alternative, was to leave the booty out boldly against the well-armed and well-equipped Quraish army of 1,000 men coming from Makkah. The Muslims had no more than 300 men, ill-armed, to oppose this force. But if they could defeat it, it would shake the selfish autocracy which was in possession of Makkah. By Allah's help they won a splendid victory, and the standard of Truth was established, never to be lowered again.