Hissan bin Kahil (may Allah have mercy on him) said: I heard Abd al-Rahman bin Samurah (may Allah be pleased with him) narrating from Sayyiduna Mu'adh (may Allah be pleased with him), from the Messenger of Allah (peace and blessings be upon him), that he (peace and blessings be upon him) said: "No servant dies bearing witness that there is no true god except Allah and that I am the Messenger of Allah, with this testimony coming from a heart that has certainty, except that he will enter Paradise." He was asked: "Did you hear this (hadith) from Mu'adh (may Allah be pleased with him)?" He said: "I heard it from Mu'adh (may Allah be pleased with him), who narrated it from the Messenger of Allah (peace and blessings be upon him)."
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17207