The Messenger of Allah (ﷺ) liked to supplicate three times and to ask pardon (of Allah) three times.
Sunan Abi Dawud Book 8, Hadith 109
← Previous Hadith The Messenger of Allah (ﷺ) commanded me to recite Mu'awwidhatan (the last two surahs of the Qur'an) after every prayer.

Sunan Abi Dawud Book 8, Hadith 108 Next Hadith → The Messenger of Allah (ﷺ) said to me: May I not teach you phrases which you utter in distress? (These are:) "Allah , Allah is my Lord, I do not associate anything as partner with Him."

Abu Dawud said: The narrator Hilal is a client of 'Umar b. 'Abd al-Aziz. The name of Ja'far, a narrator, is 'Abd Allah b. Ja'far.

Sunan Abi Dawud Book 8, Hadith 110