Abu Dharr reported that Allah's Messenger (ﷺ) was asked as to which words were the best. He said:Those for which Allah made a choice for His Angels and His servants (and the words are):" Hallowed be Allah and praise is due to Him."
حَدَّثَنَا زُهَيْرُ بْنُ حَرْبٍ، حَدَّثَنَا حَبَّانُ بْنُ هِلاَلٍ، حَدَّثَنَا وُهَيْبٌ، حَدَّثَنَا سَعِيدٌ الْجُرَيْرِيُّ، عَنْ أَبِي عَبْدِ اللَّهِ الْجِسْرِيِّ، عَنِ ابْنِ الصَّامِتِ، عَنْ أَبِي ذَرٍّ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم سُئِلَ أَىُّ الْكَلاَمِ أَفْضَلُ قَالَ " مَا اصْطَفَى اللَّهُ لِمَلاَئِكَتِهِ أَوْ لِعِبَادِهِ سُبْحَانَ اللَّهِ وَبِحَمْدِهِ " .
Muslim
The Book Pertaining to the Remembrance of Allah, Supplication, Repentance and Seeking Forgiveness • Hadith 117