Musnad Ahmad 8:124

Yahya narrated to us, from Musa—meaning al-Juhani—he said: Mus'ab ibn Sa'd narrated to me, my father narrated to me: That the Messenger of Allah (peace and blessings of Allah be upon him) said: "Is one of you unable to earn one thousand good deeds every day?" A man from those sitting with him said: "How does 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." My father said: And Ibn Numayr also said: "Or removed," and Ya'la also said: "Or removed."