Zirr bin Hubaish (may Allah have mercy on him) narrates that I asked Sayyiduna Ubayy bin Ka'b (may Allah be pleased with him) about the Mu'awwidhatayn (Surah Al-Falaq and Surah An-Naas) and said to him: "Your religious brother Ibn Mas'ud (may Allah be pleased with him) erases these two surahs from the Mushaf." Sayyiduna Ubayy bin Ka'b (may Allah be pleased with him) replied: "I asked the Messenger of Allah (ﷺ) about this, and he (ﷺ) said: (Through Jibreel) it was said to me: Say, 'Qul a'udhu...' (i.e., it was revealed). So I said, 'Qul a'udhu...'. Sayyiduna Ubayy bin Ka'b (may Allah be pleased with him) said: We also say what the Messenger of Allah (ﷺ) said."
Hadith Referenceالسنن المأثورة / باب ما جاء في الصلاة على الراحلة / 93
Hadith Takhrijصحیح بخاری، التفسير ، باب سورة قل اعوذ برب الناس، رقم : 4977۔