Sunan Abu Dawud
1515
Sahih+3

Al-Agharr al-Muzani said (Musaddad in his version of this tradition said that he was a Companion of the Prophet):The Messenger of Allah (ﷺ) said: My heart is invaded by unmindfulness, and I ask Allah's pardon a hundred times in the day

SahihAl-Albani
SahihMuhammad Muhyi Al-Din Abdul Hamid