Narrated 'Uqbah bin 'Amir:
"The Messenger of Allah (ﷺ) ordered me to recite Al-Mu'awwidhatain at the end of every Salat." (DE)
English reference (DE): Vol. 5, Book 42, Hadith 2903 (DE)
Arabic reference (DE): Book 45, Hadith 3150 (DE)