Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
tirmidhi:3585Abū ʿAmr Muslim b. ʿAmr al-Ḥadhhāʾ al-Madīnī > ʿAbdullāh b. Nāfiʿ > Ḥammād b. Abū Ḥumayd > ʿAmr b. Shuʿayb from his father from his grandfather

“The best of supplication is the supplication of the Day of ʿArafah. And the best of what I and the Prophets before me have said is: None has the right to be worshipped but Allah, Alone, without partner, to Him belongs all that exists, and to Him belongs the Praise, and He is powerful over all things. (Lā ilāha illallāh, waḥdahu lā sharīka lahu, lahul-mulku wa lahul-ḥamdu, wa huwa ʿalā kulli shai’in qadīr).’”  

الترمذي:٣٥٨٥حَدَّثَنَا أَبُو عَمْرٍو مُسْلِمُ بْنُ عَمْرٍو الْحَذَّاءُ الْمَدِينِيُّ حَدَّثَنِي عَبْدُ اللَّهِ بْنُ نَافِعٍ عَنْ حَمَّادِ بْنِ أَبِي حُمَيْدٍ عَنْ عَمْرِو بْنِ شُعَيْبٍ عَنْ أَبِيهِ عَنْ جَدِّهِ

أَنَّ النَّبِيَّ ﷺ قَالَ خَيْرُ الدُّعَاءِ دُعَاءُ يَوْمِ عَرَفَةَ وَخَيْرُ مَا قُلْتُ أَنَا وَالنَّبِيُّونَ مِنْ قَبْلِي لاَ إِلَهَ إِلاَّ اللَّهُ وَحْدَهُ لاَ شَرِيكَ لَهُ لَهُ الْمُلْكُ وَلَهُ الْحَمْدُ وَهُوَ عَلَى كُلِّ شَيْءٍ قَدِيرٌ قَالَ هَذَا حَدِيثٌ حَسَنٌ غَرِيبٌ مِنْ هَذَا الْوَجْهِ وَحَمَّادُ بْنُ أَبِي حُمَيْدٍ هُوَ مُحَمَّدُ بْنُ أَبِي حُمَيْدٍ وَهُوَ أَبُو إِبْرَاهِيمَ الأَنْصَارِيُّ الْمَدَنِيُّ وَلَيْسَ هُوَ بِالْقَوِيِّ عِنْدَ أَهْلِ الْحَدِيثِ