Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him) narrates: When the Prophet (peace and blessings be upon him) stood at night for voluntary prayers and began his prayer, after the takbir he would recite: 'Subhanaka Allahumma wa bi-hamdika, wa tabaraka ismuka, wa ta'ala jadduka, wa la ilaha ghayruka' (You are free of every imperfection, O Allah, and praise belongs to You; blessed is Your name, exalted is Your majesty, and there is no god besides You). After that he would recite 'La ilaha illallah' (There is no god but Allah) three times, and then he would recite: 'A'udhu billahi al-Sami' al-Alim min al-shaytan al-rajim, min hamzihi wa nafkhihi wa nafthihi' (I seek refuge in Allah, the All-Hearing, the All-Knowing, from the accursed Satan, from his prodding, his blowing and his spitting).
Ahmad recorded it, and its narrators are thiqat (trustworthy).