'When the hosts came to you,' meaning: Abu Sufyan and his companions. 'So We sent against them a wind,' Mujahid said: It is the easterly wind (al-Saba), which would throw them upon their faces and tear down the tents until it forced them to depart. 'And hosts which you did not see,' meaning: the angels.
﴿إِذْ جاءتكم جنود﴾ يَعْنِي: أَبَا سُفْيَانَ وَأَصْحَابَهُ ﴿فَأَرْسَلْنَا عَلَيْهِم ريحًا﴾ قَالَ مُجَاهِدٌ: وَهِي الصَّبَا، كَانَتْ تَكُبُّهُمْ عَلَى وَجُوهِهِمْ وَتَنْزِعُ الْفَسَاطِيطَ حَتَّى أَظْعَنَتْهُمْ ﴿وَجُنُودًا لَمْ تَرَوْهَا﴾ يَعْنِي: الْمَلَائِكَة.
