Reference : Hisn al-Muslim 256

وَقَالَ صلى الله عليه وسلم: كَلِمَتَانِ خَفِيفَتَانِ عَلَى اللِّسَانِ، ثَقِيلَتَانِ فِي الْمِيزَانِ، حَبِيبَتَانِ إِلَى الرَّحْمَنِ: (سُبْحَانَ اللَّهِ وَبِحَمْدِهِ)، (سُبْحانَ اللَّهِ الْعَظِيمِ)
Allah's Messenger (ﷺ) said: Two words are light on the tongue, weigh heavily in the balance, and are loved by the Most Merciful One:
Subḥānallāhi wa biḥamdih, 
Subḥānallāhi ‘l-`Aẓīm.


Allah's Messenger (ﷺ) said: Two words are light on the tongue, weigh heavily in the balance, and are loved by the Most Merciful One:

Glorified is Allah and praised is He, Glorified is Allah the Most Great.

Reference:
Al-Bukhari 7/168, Muslim 4/2072.

Chapter: Excellence of Tasbih, Tahmid, Tahlil, and Takbir