"I heard him saying" - meaning the Prophet ﷺ - "while supplicating against the Ahzab: 'O Allah, Revealer of Book! Severe is reckoning! Rout the Ahzab and shake them.'"  

سَمِعْتُهُ يَقُولُ يَعْنِي النَّبِيَّ ﷺ يَدْعُو عَلَى الأَحْزَابِ فَقَالَ اللَّهُمَّ مُنْزِلَ الْكِتَابِ سَرِيعَ الْحِسَابِ اهْزِمِ الأَحْزَابَ اللَّهُمَّ اهْزِمْهُمْ وَزَلْزِلْهُمْ