Musnad Ahmad 1153:735

Mu'ammal narrated to us, Hammad narrated to us, from Thabit, from Shahr ibn Hawshab, from his maternal uncle, from Aisha, may Allah be pleased with her, who said: They complained to the Messenger of Allah, may Allah bless him and grant him peace, about what they were experiencing of *waswasa* (whisperings/intrusive thoughts). They said: "O Messenger of Allah, we find within ourselves something that, if one of us were to fall from the sky, it would be more beloved to him than to speak of it." The Prophet, may Allah bless him and grant him peace, said: "That is pure faith."