Musannaf Ibn Abi Shaybah

It is narrated from Hazrat Ubaid bin Khalid Salmi that he said: The Messenger of Allah, peace and blessings be upon him, established brotherhood between two men. Then one of them was killed (in the way of Allah) and the other died afterwards. Then we offered his funeral prayer. So the Messenger of Allah, peace and blessings be upon him, asked: "What did you say?" The companions, may Allah be pleased with them, said: We prayed for him, saying: O Allah! Unite him with his companion. The Prophet, peace and blessings be upon him, said: "Then where will his prayers go after (the first one)? And where will his fasts go after his fasts? And where will his deeds go after his deeds?" The narrator is doubtful about the mention of fasts. "The deeds between the two of them are like the distance between the earth and the sky."