237
The Prophet ﷺ said: “The best supplication is the supplication of the Day of ʿArafah, and the best that I and the prophets before me have said is:”
لَا إِلَهَ إِلَّا اللَّهُ وَحْدَهُ لَا شَرِيكَ لَهُ، لَهُ الْمُلْكُ وَلَهُ الْحَمْدُ، وَهُوَ عَلَى كُلِّ شَيْءٍ قَدِيرٌ
La ilaha illallahu wahdahu la sharika lah, lahul-mulku walahul-hamdu, wahuwa 'ala kulli shay'in qadir
There is no deity but Allah alone, without partner; His is the dominion and His is the praise, and He has power over all things.
Source Jāmiʿ at-Tirmidhī 3585 Ḥasan
Compiler cites at-Tirmidhī; al-Albānī, Ṣaḥīḥ at-Tirmidhī 3/184 and as-Silsilah aṣ-Ṣaḥīḥah 4/6