Sayyiduna Jabir (may Allah be pleased with him) mentioned the story of Sayyiduna Mu'adh (may Allah be pleased with him); in it is that Sayyiduna Mu'adh (may Allah be pleased with him) used to pray the Isha prayer with the Prophet (peace and blessings be upon him), then return and lead his companions in prayer. One night he returned and led them in prayer, and a young man from his people prayed behind him. When the prayer became long for the young man, he left the congregation, prayed his own prayer, took hold of his camel's halter and went away. When Sayyiduna Mu'adh (may Allah be pleased with him) finished the prayer, he was told about it, and he said: "This is a hypocrite; I will inform the Prophet (peace and blessings be upon him) about him." And the young man said: "I too will inform the Messenger of Allah (peace and blessings be upon him) of what he did." In the morning they went to the Prophet (peace and blessings be upon him), and Sayyiduna Mu'adh (may Allah be pleased with him) told the Prophet (peace and blessings be upon him) what the young man had done. The young man said: "O Messenger of Allah! He stays a long time with you (peace and blessings be upon him), then comes back and leads us in a long prayer." He (peace and blessings be upon him) said: "O Mu'adh! Are you one who puts people to trial?" And he asked the young man: "O son of my brother! What do you do when you pray?" He said: "I recite Surah al-Fatihah, ask Allah for Paradise and seek refuge with Him from the Fire. I do not understand your humming and the humming of Mu'adh." The Prophet (peace and blessings be upon him) said: "Mu'adh and I revolve around these two," or he said something like it. The narrator says: The young man said: "But Mu'adh will come to know when the people come, and they have been told that the enemy has come." The narrator says: They came, and the young man was martyred. After that the Prophet (peace and blessings be upon him) said to Sayyiduna Mu'adh (may Allah be pleased with him): "What became of the one who disputed with me and with you?" Sayyiduna Mu'adh (may Allah be pleased with him) said: "He was true to Allah and I spoke falsely; he has been martyred."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 5273