Du'a during Arafah

لَا إِلَهَ إِلَّا اللَّهُ وَحْدَهُ لَا شَرِيكَ لَهُ، لَهُ الْمُلْكُ وَلَهُ الْحَمْدُ، بِيَدِهِ الْخَيْرُ، يُحْيِي وَيُمِيتُ، وَهُوَ عَلَى كُلِّ شَيْءٍ قَدِيرٌ

La ilaha illal-lahu wahdahu la sharika lah, lahul-mulku wa lahul-hamdu, biyadihil-khayru, yuhyi wa yumitu, wa huwa 'ala kulli shay'in qadir

There is no god but Allah alone, with no partner or associate. His is the dominion, to Him all praise is due, all goodness is in His hand, He grants life and causes death, and He has power over all things.

Adapted (adds "all goodness is in His hand" and "He grants life and causes death") from Jāmiʿ al-Tirmidhī 3585, which reads "لَا إِلَهَ إِلَّا اللَّهُ وَحْدَهُ لَا شَرِيكَ لَهُ، لَهُ الْمُلْكُ وَلَهُ الْحَمْدُ، وَهُوَ عَلَى كُلِّ شَيْءٍ قَدِيرٌ" (There is no god but Allah alone, with no partner. His is the dominion and His is the praise, and He has power over all things).