Musnad Ahmad 32:444

Bahz narrated to us, Sulayman ibn al-Mughirah narrated to us, Thabit narrated to us, from Anas ibn Malik, that ‘Itban complained of his eye, so he sent to the Messenger of Allah (may Allah bless him and grant him peace) and mentioned to him what had afflicted him and said: "O Messenger of Allah, come and pray in my house, so that I may take it as a place of prayer." He said: So the Messenger of Allah (may Allah bless him and grant him peace) came, along with whoever Allah willed of his companions. The Messenger of Allah (may Allah bless him and grant him peace) stood to pray, while his companions were talking among themselves. They began to mention what they were encountering from the hypocrites, and they attributed the greatest part of that to Malik ibn Dukhayshim. The Messenger of Allah (may Allah bless him and grant him peace) finished [his prayer] and said: "Does he not testify that there is no god but Allah and that I am the Messenger of Allah?" A speaker said: "Yes, but it is not from his heart." The Messenger of Allah (may Allah bless him and grant him peace) said: "Whoever testifies that there is no god but Allah and that I am the Messenger of Allah, the Fire will never consume him," or he said: "He will never enter the Fire."