Surah Muhammad (Muhammad ) 47 : 21

The contents of this Surah testify that it was sent down after the Hijrah at Madinah at the time when the fighting had been enjoined, though active fighting had not yet been undertaken.

The conditions at the time when this Surah was sent down were such that the Muslims were being made the target of persecution and tyranny in Makkah in particular and in Arabia in general, and life had become miserable for them. Although the Muslims had emigrated to the haven of Madinah from every side, the disbelieving Quraysh were not prepared to leave them alone and let them live in peace even there. Thus, the small settlement of Madinah was hemmed in by the enemy, who was bent upon exterminating it completely. The only alternative left with the Muslims were that either they should surrender to the forces of ignorance, giving up their mission of preaching the true Faith, or even following it in their private lives, or should rise to wage a war at the cost of their lives to settle finally and forever whether Islam would stay in Arabia or the creed of ignorance. On this occasion God showed the Muslims the same way of resolution and will, which is the only way for the true believers. He first permitted them to fight in Surah 22: al-Hajj (The Pilgrimage): 39 and then enjoined fighting in Surah 2: al-Baqarah (The Cow): 190. But at that time everyone knew full well what it meant to wage a war in those conditions. There were only a handful of Muslims in Madinah, who could not muster even a thousand soldiers; yet they were being urged to take up the sword and clash against the pagan forces of the whole of Arabia. Then the kind of the weapons needed to equip its soldiers for war could hardly be afforded by the town in which hundreds of emigrants were still homeless and unsettled even by resort to starving its members at a time when it had been boycotted economically by the Arabs on all sides.