Abu Dawud
Prayer
Book Number: 002 / Hadith Number: 1363
Narated By 'Aisha : The Apostle of Allah (pbuh) said: Choose such actions as you are capable of performing, for Allah does not grow weary till you do. The acts most pleasing to Allah are those which are done most continuously, even if they mount to little. Whenever he began an action, he would do it continuously.