Sa'd bin Abu Waqqas (May Allah be pleased with him) reported:
A bedouin came to the Messenger of Allah ﷺ and said to him, "Teach me a few words to recite frequently." He ﷺ said, "Say: "La ilaha illallahu wahdahu la sharika lahu; Allahu Akbar kabiran, wal-hamdu lillahi kathiran, wa subhan-Allahi Rabbil-'alamin; wa la hawla wa la quwwata illa billahil-'Azizil-Hakim (there is no true god except Allah the One and He has no partner with Him; Allah is the Greatest and greatness is for Him. All praise is due to Him. Allah, the Rubb of the worlds is free from imperfection; there is no might and power but that of Allah, the All-Powerful and the All-Wise.)"' The bedouin said: "All of these for my Rubb. But what is for me?" Thereupon he (Messenger of Allah ﷺ) said, "You should say: 'Allahummaghfir li, warhamni, wahdini, warzuqni (O Allah! Grant me pardon, have mercy upon me, direct me to righteousness and provide me subsistence)'."

[Muslim].

وعن سعد بن أبي وقاص رضي الله عنه قال: جاء أعرابي إلى رسول الله ﷺ فقال: علمني كلامًا أقوله. قال: "قل لا إله إلا الله وحده لا شريك له، الله أكبر كبيرا والحمد لله كثيرا وسبحان الله رب العالمين، ولا حول ولا قوة إلا بالله العزيز الحكيم” قال فهؤلاء لربي، فما لي؟ قال: "قل اللهم اغفر لي، وارحمني، واهدني، وارزقني" ((رواه مسلم)).