The Battle of Al-Ahzab (The Confederates), also known as Al-Khandaq (The Ditch)
وَحَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، وَابْنُ، بَشَّارٍ - وَاللَّفْظُ لاِبْنِ الْمُثَنَّى - حَدَّثَنَا مُحَمَّدُ بْنُ، جَعْفَرٍ حَدَّثَنَا شُعْبَةُ، عَنْ مُعَاوِيَةَ بْنِ قُرَّةَ، عَنْ أَنَسِ بْنِ مَالِكٍ، عَنِ النَّبِيِّ صلى الله عليه وسلم أَنَّهُ قَالَ " اللَّهُمَّ لاَ عَيْشَ إِلاَّ عَيْشُ الآخِرَهْ فَاغْفِرْ لِلأَنْصَارِ وَالْمُهَاجِرَهْ " .
It has been narrated on the authority of Anas b. Malik that the Messenger of Allah (ﷺ) said: O God, there is no life, but the life of the Hereafter, So forgive Thou the Ansar and the Muhajirs.