Musnad Ahmad 1034:130

'Abd al-Rahman narrated to us, from Sufyan, from Abu Ishaq, from 'Ubayd Abu al-Mughirah, from Hudhayfah, who said: I was a man with a sharp tongue toward my family, so I said: "O Messenger of Allah, I fear that my tongue will cause me to enter the Fire." He said: "Where are you regarding seeking forgiveness? Verily, I seek forgiveness from Allah one hundred times a day." Abu Ishaq said: I mentioned this to Abu Burdah, and he said: "And I repent to Him."