Musnad Ahmad 8:173

Abdullah ibn Numayr narrated to us, Musa narrated to us, from Mus'ab ibn Sa'd, my father narrated to me, he said: We were sitting with the Messenger of Allah, may Allah bless him and grant him peace, and he said: "Is one of you unable to earn one thousand good deeds every day?" A questioner from those sitting with him said: O Prophet of Allah, how can one of us earn one thousand good deeds? He said: "He performs one hundred tasbihs (sayings of SubhanAllah), and one thousand good deeds are written for him, or one thousand sins are removed from him."