The Reward for Glorifying, Praising, Declaring God’s Unity and His Greatness - Section 2 Mishkat al-Masabih 2306
Arabic hadith text
وَعَنْ جَابِرٍ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ:" أَفْضَلُ الذِّكْرِ: لَا إِلَهَ إِلَّا اللَّهُ وَأَفْضَلُ الدُّعَاءِ: الْحَمْدُ لِلَّهِ ". رَوَاهُ التِّرْمِذِيّ وَابْن مَاجَه
Translation
Jabir reported God’s messenger as saying that the most excellent way to make mention of God is to say, “There is no god but God” and that the most excellent supplication is “Praise be to God.” Tirmidhi and Ibn Majah transmitted it.