اللهم أنت ربي. لا اله الا أنت. عليك توكلت وأنت رب العرش العظيم
Allāhumma anta rabbī, lā ilāha illā anta, ʿalayka tawakkaltu wa anta rabbu l-ʿarshi l-ʿaẓīm
“O God, You are my Lord; there is no god but You; in You I put my trust, Lord of the great Throne”: said when one sets out on an activity.
What it means
Muslims say these words at the start of an undertaking. They declare God to be Lord, affirm that there is no god but Him, and place trust (tawakkul) in Him. The last words echo the end of surah 9: “I have put my trust in Him, and He is Lord of the Great Throne” (9:129). The Quran also instructs the believer, “When you have decided, put your trust in God” (3:159). The prayer joins effort with reliance on God for the result.
Term and Arabic as listed in Ismail al Faruqi, Toward Islamic English (International Institute of Islamic Thought, 1995), p. 59, listed as ALLAHUMMA ANTA RABBĪ. LĀ ILAHA ILLĀ ANT. ‘ALAYKA TAWAKKALTU WA ANTA RABB AL ‘ARSH AL ‘AẒĪM.. The definition is restated here.