The Messenger of Allah (ﷺ) commanded me to recite Mu'awwidhatan (the last two surahs of the Quran) after every prayer.
Sunan Abi Dawud Book 8, Hadith 108
← Previous Hadith By Allah, I love you, Mu'adh. I give some instruction to you. Never leave to recite this supplication after every (prescribed) prayer: "O Allah, help me in remembering You, in giving You thanks, and worshipping You well."

Mu'adh willed this supplication to the narrator al-Sunabihi and al-Sunabihi to 'Abu Abd al-Rahman.

Sunan Abi Dawud Book 8, Hadith 107 Next Hadith → 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