Musnad Ahmad 1496

Mus"ab bin Sa"d narrated from Sa"d that The Messenger of Allah (ﷺ) said: "Will one of you be incapable of earning one thousand hasanah in one day?” He said: Who is able to do that? He said: “He says tasbeeh one hundred times, and it will be recorded as one thousand hasanah (good deeds) and will erase one thousand sayyi"ahs (bad deeds)."