Ali bin Zayd (may Allah have mercy on him) says: We were with Sayyiduna Anas bin Malik (may Allah be pleased with him), and he said to his son Abu Bakr: Narrate to them the hadith of Itban bin Malik al-Ansari (may Allah be pleased with him). So Abu Bakr narrated this hadith to us while Sayyiduna Anas (may Allah be pleased with him) was present. He said: I went out with my father to Syria. When he was returning from Syria, Sayyiduna Mahmud bin al-Rabi' al-Ansari (may Allah be pleased with him) walked with us and came to see us off. When he was about to part from us, he said: Shall I not narrate to you the hadith of Itban bin Malik (may Allah be pleased with him)? We said: Certainly, do narrate it. He said: He told me that his eyesight went during the time of the Messenger of Allah (peace and blessings be upon him), so he said: O Messenger of Allah, if only you would come to my house, mark out a place of prayer for me in it and pray there, so that I may take it as a mosque; my eyesight has gone and I lack the strength to go to the mosque. The Messenger of Allah (peace and blessings be upon him) promised him a day on which he would come. When that day came, his (peace and blessings be upon him) Companions flocked to him (peace and blessings be upon him) and gathered in my house. The Messenger of Allah (peace and blessings be upon him) came and heard them discussing who in Madinah was the harshest against the Companions of the Messenger of Allah (peace and blessings be upon him) and his greatest enemy, and they turned the matter to Malik bin al-Dukhshum. The Prophet (peace and blessings be upon him) asked them: What are you talking about? Then he said: "Does he not testify that there is no true god but Allah and that I am the Messenger of Allah?" They said: O Messenger of Allah, he is a companion (of the hypocrites). He (peace and blessings be upon him) said: "Does he not testify that there is no true god but Allah and that I am the Messenger of Allah?" They said: Yes. He (peace and blessings be upon him) said: "By the One in whose Hand is my soul, if he says it truthfully from his heart, the Fire will never consume him." Anas (may Allah be pleased with him) said to me: Remember this hadith, for it is one of the treasures of knowledge. When we reached Madinah, we found Itban bin Malik (may Allah be pleased with him) alive, so I said to my father: Will you come to Itban so that we may ask him about the hadith that Mahmud narrated to us from him? So we went and asked him, and he narrated it to us himself.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 15136