Musannaf Ibn Abi Shayba 21:321

Abu al-Ahwas narrated to us, from Abu Ishaq, from Abu al-Mughirah, from Hudhayfah, who said: I complained to the Messenger of Allah (may Allah bless him and grant him peace) about the sharpness of my tongue. He said: "Where are you regarding seeking forgiveness? Verily, I seek forgiveness from Allah one hundred times every day."