Musnad Ahmad 1012:46

Yunus ibn Muhammad narrated to us, Layth narrated to us, from Ibn ‘Ajlan, from Muhammad ibn Yahya ibn Habban, from Ibn Muhayriz, from al-Sunabihī, that he said: I entered upon ‘Ubadah ibn al-Samit while he was in the state of death, so I wept. He said: "Wait, why do you weep? By Allah, if I am called to testify, I will surely testify for you; and if I am granted the right of intercession, I will surely intercede for you; and if I am able, I will surely benefit you." Then he said: "By Allah, there is no hadith I heard from the Messenger of Allah (peace and blessings of Allah be upon him) in which there is good for you, except that I have narrated it to you, save for one hadith which I will narrate to you today, now that my soul is being encompassed [by death]. I heard the Messenger of Allah (peace and blessings of Allah be upon him) say: 'Whoever testifies that there is no god but Allah and that Muhammad is the Messenger of Allah, the Fire is forbidden to him.'"