مُسْنَدُ أَحْمَدَ
Musnad Ahmad 1563
Musnad Abu Ishaq Sa'd bin Abi Waqqas
Mus"ab bin Sa"d narrated: My father told me that the Messenger of Allah (ﷺ) said: “Will one of you be incapable of earning one thousand hasanahs in one day?" One of the people who were sitting with him said: Who is able to do that? He said: “He says tasbeeh one hundred times, and it will be recorded as one thousand hasanahs (good deeds) or it will erase one thousand sayyi"ahs (bad deeds]."
Musnad Ahmad 1563Sahih (Darussalam) [Musliim (2698)|