Musnad Abu Ya'la al-Mawsili 150:147

'Abd al-A'la narrated to us, from 'Abd al-Rahman ibn Abi al-Zinad, from Hisham ibn 'Urwah, from 'Urwah, that a woman from Banu Asad was with 'Aishah. The Messenger of Allah (may Allah bless him and grant him peace) entered and said, "Who is this?" 'Aishah said, "This is so-and-so; she does not sleep, mentioning her prayer." The Messenger of Allah (may Allah bless him and grant him peace) said, "Take upon yourselves what you can bear, for Allah does not grow weary until you grow weary." 'Aishah said, "The most beloved religion to Him is that which its practitioner persists in."