Translation:

7. Behold! Allah promised you one of the two (enemy) parties that it should be yours: ye wished that the one unarmed should be yours but Allah willed to justify the truth according to His words and to cut off the roots of the unbelievers.

Notes (Tafseer)

1183. 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.