Sahih Muslim Book - 32, Hadith - 4675

وَحَدَّثَنَا يَحْيَى بْنُ يَحْيَى وَشَيْبَانُ بْنُ فَرُّوخَ قَالَ يَحْيَى أَخْبَرَنَا وَقَالَ شَيْبَانُ حَدَّثَنَا عَبْدُ الْوَارِثِ عَنْ أَبِى التَّيَّاحِ حَدَّثَنَا أَنَسُ بْنُ مَالِكٍ قَالَ كَانُوا يَرْتَجِزُونَ وَرَسُولُ اللَّهِ -صلى الله عليه وسلم- مَعَهُمْ وَهُمْ يَقُولُونَ اللَّهُمَّ لاَ خَيْرَ إِلاَّ خَيْرُ الآخِرَهْ فَانْصُرِ الأَنْصَارَ وَالْمُهَاجِرَهْ وَفِى حَدِيثِ شَيْبَانَ بَدَلَ فَانْصُرْ فَاغْفِرْ.

Anas bin Malik said: "They were chanting lines of poetry, when the Messenger of Allah (s.a.w) was with them, and they were saying: 'O Allah, there is no goodness but the goodness of the Hereafter So help the Ansar and the Muhajirin."' According to the Hadith of Shaiban, instead of "help"they said "forgive."