حَدَّثَنَا مُحَمَّدُ بْنُ كَثِيرٍ، أَخْبَرَنَا شُعْبَةُ، عَنْ عَمْرِو بْنِ مُرَّةَ، قَالَ سَمِعْتُ عَمْرَو بْنَ مَيْمُونٍ، عَنْ عَبْدِ اللَّهِ بْنِ رُبَيِّعَةَ، عَنْ عُبَيْدِ بْنِ خَالِدٍ السُّلَمِيِّ، قَالَ ‏:‏ آخَى رَسُولُ اللَّهِ صلى الله عليه وسلم بَيْنَ رَجُلَيْنِ فَقُتِلَ أَحَدُهُمَا وَمَاتَ الآخَرُ بَعْدَهُ بِجُمُعَةٍ أَوْ نَحْوِهَا، فَصَلَّيْنَا عَلَيْهِ، فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏:‏ ‏"‏ مَا قُلْتُمْ ‏"‏ ‏.‏ فَقُلْنَا ‏:‏ دَعَوْنَا لَهُ، وَقُلْنَا ‏:‏ اللَّهُمَّ اغْفِرْ لَهُ وَأَلْحِقْهُ بِصَاحِبِهِ ‏.‏ فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏:‏ ‏"‏ فَأَيْنَ صَلاَتُهُ بَعْدَ صَلاَتِهِ وَصَوْمُهُ بَعْدَ صَوْمِهِ ‏"‏ ‏.‏ شَكَّ شُعْبَةُ فِي صَوْمِهِ ‏:‏ ‏"‏ وَعَمَلُهُ بَعْدَ عَمَلِهِ إِنَّ بَيْنَهُمَا كَمَا بَيْنَ السَّمَاءِ وَالأَرْضِ ‏"‏ ‏.‏

Narrated Ubaydullah ibn Khalid as-Sulami: The Messenger of Allah (PBUH) made a brotherhood between two men, one of whom was killed (in Allah's path), and a week or thereabouts later the other died, and we prayed at his funeral). The Messenger of Allah (PBUH) asked: What did you say? We replied: We prayed for him and said: O Allah, forgive him, and join him to his companion. The Messenger of Allah (PBUH) said: What about his prayers since the time the other died, and his fasting since the time the other died--the narrator Shu'bah doubted the words, "his fasting--and his deeds since the time the other died. The distance between them is just like the distance between heaven and earth. Translation Not Available

Book Ref: Sunan Abi Dawud Book 15 Hadith 2524
Web Ref:  Sunan Abi Dawud Book 14 Hadith 2518