Mishkat al-Masabih 2298
He reported God’s messenger as saying, "Two expressions which are light on the tongue but heavy in the scale are dear to the Compassionate One:
Glory be to God, and I begin with praise of Him; and Glory be to God the Incomparably Great." 

(Bukhari and Muslim.)
وَعَنْهُ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: 
" كَلِمَتَانِ خَفِيفَتَانِ عَلَى اللِّسَانِ ثَقِيلَتَانِ فِي الْمِيزَانِ حَبِيبَتَانِ إِلَى الرَّحْمَنِ: سُبْحَانَهُ الله وَبِحَمْدِهِ سُبْحَانَهُ الله الْعَظِيم "