سُبْحَانَ رَبَّيَ الْعَظِيمِ (ثلاثا)

How perfect my Lord is, The Supreme. (Three times)

Reference: Abū Dāwud (#871), al-Tirmidhī (#262), al-Nisā'i (1/190), Ibn Mājah (#888), and Aḥmad (#394, 5/382,394). Also see Ṣaḥīḥ al-Tirmidhī (1/83).