Sahih Bukhari Volume 2, Book 21, Hadith Number 279.
When the neighbors got the news that Allah’s Apostle was in my house, they poured it till there were a great number of men in the house. One of them said, ‘What is wrong with Malik, for I do not see him?’ One of them replied, ‘He is a hypocrite and does not love Allah and His Apostle.’ On that Allah’s Apostle said, ‘Don’t say this. Haven’t you seen that he said, ‘None has the right to be worshipped but Allah for Allah’s sake only.’ The man replied, ‘Allah and His Apostle know better; but by Allah, we never saw him but helping and talking with the hypocrites.’ Allah’s Apostle replied, ‘No doubt, whoever says. None has the right to be worshipped but Allah, and by that he wants the pleasures of Allah, then Allah will save him from Hell.” Mahmud added, “I told the above narration to some people, one of whom was Ab-u Aiyub, the companion of Allah’s Apostle in the battle in which he (Ab-u Aiyub) died and Yazid bin Mu’aw7ya was their leader in Roman Territory. Abu Aiyub denounced the narration and said, ‘I doubt that Allah’s Apostle ever said what you have said.’ I felt that too much, and I vowed to Allah that if I remained alive in that holy battle, I would (go to Medina and) ask Itban bin Malik if he was still living in the mosque of his people. So when he returned, I assumed Ihram for Hajj or ‘Umra and then I proceeded on till I reached Medina. I went to Bani Salim and Itban bin Malik, who was by then an old blind man, was leading his people in the prayer. When he finished the prayer, I greeted him and introduced myself to him and then asked him about that narration. He told that narration again in the same manner as he had narrated it the first time.”