Surat Al Anfal: (11-12)

{إِذْ يُغَشِّيكُمُ النُّعَاسَ أَمَنَةً مِّنْهُ وَيُنَزِّلُ عَلَيْكُم مِّن السَّمَاء مَاء لِّيُطَهِّرَكُم بِهِ وَيُذْهِبَ عَنكُمْ رِجْزَ الشَّيْطَانِ وَلِيَرْبِطَ عَلَى قُلُوبِكُمْ وَيُثَبِّتَ بِهِ الأَقْدَامَ} [الأنفال : 11]

11- And remember when your Lord cast somnolence upon you to make you feel secure after the fear that had hit you. He also sent down rain because you needed water for ablution and ritual complete bathing. He also made satanic insinuations go away after Satan had frightened you of thirst, but Allah strengthened your hearts with certainty, patience, and trust in Allah's Power. Moreover, Allah made your feet firm so as not to sink in sand during war.

The polytheists preceded the believers to the water of Badr, and Muslims became afraid of thirst, so Allah sent down rain until it filled the valley. Then the believers drank, washed up, performed ablution, watered their animals, and filled their water skins until they were comforted and the satanic insinuations went away. Rain was sent down to them before they fell asleep.

The land in which Muslims camped were full of sand, so they were able to walk on it after rain as they wished, but the place in which the polytheists camped was full of dust and mud. When the rain came down, mud became more slippery and they could not walk as they wish.

{إِذْ يُوحِي رَبُّكَ إِلَى الْمَلآئِكَةِ أَنِّي مَعَكُمْ فَثَبِّتُواْ الَّذِينَ آمَنُواْ سَأُلْقِي فِي قُلُوبِ الَّذِينَ كَفَرُواْ الرَّعْبَ فَاضْرِبُواْ فَوْقَ الأَعْنَاقِ وَاضْرِبُواْ مِنْهُمْ كُلَّ بَنَانٍ} [الأنفال : 12]

12- O Prophet, remember when your Lord said to the angels who were sent to aid Muslims that I am with you by help and support, so strengthen the hearts of the believers, make them firm, and give them glad tiding with victory, for I shall cast fear and horror in the hearts of the polytheists until they expect defeat anytime. So, strike their heads and necks with swords and cut off every joint of their hands and legs.