Musannaf Ibn Abi Shayba 21:312

Marwan ibn Mu'awiyah narrated to us, from Musa al-Juhani, from Mus'ab ibn Sa'd, from his father, who said: We were with the Messenger of Allah, may Allah bless him and grant him peace, and he said to us, "Is one of you unable to earn one thousand good deeds in a day?" A questioner asked him, "How can one of us earn one thousand good deeds?" He said, "He glorifies Allah (says SubhanAllah) one hundred times, and one thousand good deeds are written for him, and one thousand sins are removed from him."