Sahih Muslim, Chapter: Faith (Kitab Al Iman)

that he came to Medina and said: Something had gone wrong with my eyesight. I, therefore, sent (a message to the Holy Prophet): Verily it is my ardent desire that you should kindly grace my house with your presence and observe prayer there so, that I should make that corner a place of worship. He said: The Prophet (may peace be upon him) came there, and those amongst the Companions whom Allah willed also accompanied him. He entered (my place) and offered prayer at my residence and his Companions began to talk amongst themselves (and this conversation centered round hypocrites), and then the conspicuous one, Malik b. Dukhshum was made the target and they wished that he (the Holy Prophet) should curse him and he should die or he should meet some calamity. In the meanwhile the Messenger of Allah (may peace and blessings be upon him) completed his prayer and said: Does Malik b. Dukhshum not testify the fact that there is no god but Allah and verily I am the messenger of Allah. They replied: He makes a profession of it (no doubt) but does not do it out of (sincere) heart. He (the Holy Prophet) said: He who testifies that there is no god but Allah and I am the messenger of Allah would not enter Hell or its (flames) would not consume him. Anas said: This hadith impressed me very much and I told my son to write it down.