Musnad Ahmad 1612

It was narrated from Mus"ab bin Sa"d that his father said: We were sitting with the Messenger of Allah (ﷺ) and he said: "Will one of you be incapable of earning one thousand hasanahs every day?" One of the people sitting with him asked him. O Messenger of Allah, how could one of us earn one thousand hasanahs every day? He said: "He says tasbeeh one hundred times, and it will be recorded as one thousand hasanahs (good deeds] or will erase one thousand sayyi"ahs (bad deeds).”