It is narrated from Hazrat Uqbah bin Amir (may Allah be pleased with him) that the Prophet (peace and blessings of Allah be upon him) commanded me to recite the Mu'awwidhat (the Surahs in which the words "Qul A'udhu" occur) after every prayer.
Hadith Referenceمسند احمد / مسند الشاميين / 17417
Hadith Gradingحکم دارالسلام:حديث صحيح، وهذا إسناد حسن، م: 814