Abu Dawud and at-Tirmidhi report something similar from 'Aishah (RA) that Allah's Messenger (ﷺ) used to recite a Surat in every Rak'at and in the last (third) Rak'at he would recite Qul Huwa Allahu Ahad (Surat al-Ikhlas) and al-Mu'awwidhatain.