قَالَ النَّبِيُّ صلى الله عليه وسلم: ((خَيْرُ الدُّعَاءِ دُعَاءُ يَوْمِ عَرَفَةَ، وَخَيْرُ مَا قُلْتُ أَنَا وَالنَّبيُّونَ مِنْ قَبْلِي: لاَ إِلَهَ إِلاَّ اللَّهُ وَحْدَهُ لاَ شَرِيكَ لَهُ، لَهُ الْمُلْكُ وَلَهُ الْحَمْدُ وَهُوَ عَلَى كُلِّ شَيْءٍ قَدِيرٌ)).
Transliteration
(The best of supplications is the supplication on the day of AAarafah and the best which I and the Prophets before me have said (is): (La ilaha illal-lahu wahdahu la shareeka lah, lahul-mulku walahul-hamd, wahuwa AAala kulli shayin qadeer.))
Translation
(The best of supplications is the supplication on the day of AAarafah and the best which I and the Prophets before me have said (is): (None has the right to be worshipped except Allah, alone, without partner. To Him belongs all praise and sovereignty and He is over all things omnipotent.))
Source
Hisnul Muslim (Fortress of the Muslim), No. 237 — chapter “Invocation to be recited on the Day of Arafat”. hisnmuslim.com
Related Duas
((لَبَّيْكَ اللَّهُمَّ لَبَّيْكَ، لَبَّيْكَ لاَ شَرِيكَ لَكَ لَبَّيْكَ، إِنَّ الْحَمْدَ، وَالنِّعْمَةَ، لَكَ وَالْمُلْكَ، لاَ شَرِيكَ لَكَ)).
(Here I am O Allah, (in response to Your call), here I am. Here I am, You have no partner, here I am. Verily all praise, grace and sovereignty belong to You. You have no partner.)
Hisnul Muslim · No. 233
((طَافَ النَّبيُّ صلى الله عليه وسلم بِالْبَيْتِ عَلَى بَعِيرٍ كُلَّمَا أَتَى الرُّكْنَ أَشَارَ إِلَيْهِ بِشَيْءٍ عِنْدَهُ وَكَبَّرَ)).
(The Prophet circled the KaAAbah on a camel, every time he reached the black stone he would point to it with his staff and say: (Allah is the greatest))
Hisnul Muslim · No. 234
((﴿رَبَّنَا آتِنَا فِي الدُّنْيَا حَسَنَةً وَفِي الْآخِرَةِ حَسَنَةً وَقِنَا عَذَابَ النَّارِ﴾)).
The Prophet PBUH used to say between the Yemeni corner and the black stone: (O our Lord, grant us the best in this life and the best in the next life, and protect us from the punishment of the Fire.)
Hisnul Muslim · No. 235