Musnad Ahmad 1153:1413

Muhammad ibn Ja’far and Bahz narrated to us, they said: Shu’bah narrated to us. Bahz said: Sa’d ibn Ibrahim informed me that he heard Abu Salamah narrating from ‘Aishah, that the Messenger of Allah (ﷺ) was asked: "Which deed is most beloved to Allah?" He said: "The most constant of them, even if it is little." Bahz said: "That which is persisted in." And he said: "Take upon yourselves of the deeds that which you are able to bear."