Sunan an-Nasa'i 1985
It was narrated from 'Amr bin Maimun from "Abdullah bin Rubayy'ah As-Sulami, who was also one of the Companions of Allah's Messenger from 'Ubaid bin Khalid As-Sulami, that:
the Messenger of Allah established the bond of brotherhood between two men. One of them was killed and the other died after him. We offered the funeral prayer for him, and the Prophet said: "What did you say?" They said: "O Allah, forgive him; O Allah, have mercy on him; O Allah, join him with his companion." The Prophet said: "Where is his Salah in comparison to his companion's Salah? Where are his deeds in comparison to his companion's deeds? Indeed the difference between heaven and Earth." (One of narrators) 'Amr bin Maimun Said: "I was happy with that because he raised it for me."
أَخْبَرَنَا سُوَيْدُ بْنُ نَصْرٍ، قَالَ أَنْبَأَنَا عَبْدُ اللَّهِ، قَالَ حَدَّثَنَا شُعْبَةُ، عَنْ عَمْرِو بْنِ مُرَّةَ، قَالَ سَمِعْتُ عَمْرَو بْنَ مَيْمُونٍ، يُحَدِّثُ عَنْ عَبْدِ اللَّهِ بْنِ رُبَيِّعَةَ السُّلَمِيِّ، وَكَانَ، مِنْ أَصْحَابِ رَسُولِ اللَّهِ صلى الله عليه وسلم عَنْ عُبَيْدِ بْنِ خَالِدٍ السُّلَمِيِّ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم آخَى بَيْنَ رَجُلَيْنِ فَقُتِلَ أَحَدُهُمَا وَمَاتَ الآخَرُ بَعْدَهُ فَصَلَّيْنَا عَلَيْهِ فَقَالَ النَّبِيُّ صلى الله عليه وسلم ‏"‏ مَا قُلْتُمْ ‏"‏ ‏.‏ قَالُوا دَعَوْنَا لَهُ اللَّهُمَّ اغْفِرْ لَهُ اللَّهُمَّ ارْحَمْهُ اللَّهُمَّ أَلْحِقْهُ بِصَاحِبِهِ فَقَالَ النَّبِيُّ صلى الله عليه وسلم ‏"‏ فَأَيْنَ صَلاَتُهُ بَعْدَ صَلاَتِهِ وَأَيْنَ عَمَلُهُ بَعْدَ عَمَلِهِ فَلَمَا بَيْنَهُمَا كَمَا بَيْنَ السَّمَاءِ وَالأَرْضِ ‏"‏ ‏.‏ قَالَ عَمْرُو بْنُ مَيْمُونٍ أَعْجَبَنِي لأَنَّهُ أَسْنَدَ لِي ‏.‏