عَنْ أَبِي ذَرٍّ رَضِيَ اللَّهُ عَنْهُ قَالَ سُئِلَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ أَيُّ الْكَلَامِ أَفْضَلُ قَالَ مَا اصْطَفَاهُ اللَّهُ عَزَّ وَجَلَّ لِعِبَادِهِ سُبْحَانَ اللَّهِ وَبِحَمْدِهِ
It is narrated from Sayyiduna Abu Dharr (may Allah be pleased with him) that when the Messenger of Allah (peace and blessings be upon him) was asked, "Which speech is the best?" he (peace and blessings be upon him) replied: "The speech which Allah Almighty has chosen for His servants, that is, Subhanallahi wa bihamdihi."