Muhammad bin Muslim (may Allah have mercy on him) narrates that Sayyiduna Mahmud bin al-Rabi' al-Ansari (may Allah be pleased with him) told him that Sayyiduna Itban bin Malik (may Allah be pleased with him), who was a Companion of the Messenger of Allah (peace and blessings be upon him) and one of the Ansar who were present at Badr, came to the Messenger of Allah (peace and blessings be upon him) and said: O Messenger of Allah, my eyesight has become weak and I lead my people in prayer; when the rains come, the valley between me and them floods, and I cannot go to their mosque and lead them in prayer. So, O Messenger of Allah, I would like you to pray at a place that I may take as a place of prayer. The Messenger of Allah (peace and blessings be upon him) said: "I will do so, if Allah wills." Itban says: So the Messenger of Allah (peace and blessings be upon him), Abu Bakr and Umar (may Allah be pleased with them both) came when the day had risen. The Messenger of Allah (peace and blessings be upon him) asked permission and I gave him permission. He (peace and blessings be upon him) entered the house without sitting down and said: "Where in your house would you like me to pray?" I pointed to a corner of the house, so the Messenger of Allah (peace and blessings be upon him) stood and said the takbir; we stood and formed a row, and we prayed two rak'ahs. Then a number of people gathered in the house, and one of them said: Where is Malik bin al-Dukhayshin? One of them said: He is a hypocrite who does not love Allah and His Messenger. The Messenger of Allah (peace and blessings be upon him) said: "Do not say that; do you not see that he has said 'La ilaha illallah', seeking thereby the pleasure of Allah?" He said: Allah knows best; we see his inclination and his sincere counsel directed towards the hypocrites. The Messenger of Allah (peace and blessings be upon him) said: "Indeed Allah has made forbidden to the Fire the one who says 'La ilaha illallah', seeking thereby the pleasure of Allah." Muhammad says: Then I asked al-Husayn bin Muhammad, who was one of the chiefs of Banu Salim, about the hadith of Mahmud, and he confirmed it.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 15144