Musnad Ahmad 30:2034

Abu al-Jawwab al-Dabbi al-Ahwas ibn Jawwab narrated to us, he said: Ammar ibn Zurayq narrated to us, from al-A’mash, from Abu Salih, from Abu Hurayrah, who said: A man came to the Prophet, may Allah bless him and grant him peace, and said: "O Messenger of Allah, I have thoughts within myself—that I would rather fall from the sky than speak of them." He said: "That is clear faith."