Musnad Ahmad 1153:2260

Muhammad ibn Yazid—meaning al-Wasiti—narrated to us, from Sufyan ibn ‘Uyaynah, from al-Zuhri, from ‘Urwah, from ‘Aishah, who said: The Messenger of Allah (may Allah bless him and grant him peace) said to me: "O ‘Aishah, if you have committed a sin, then seek forgiveness from Allah, for the repentance from sin is remorse and seeking forgiveness."