Dua at the start of the prayer
It was narrated from ‘Aishah that when the Prophet (ﷺ) started Salat he would say:
سُبْحانَكَ اللَّهُمَّ وَبِحَمْدِكَ، وَتَبارَكَ اسْمُكَ، وَتَعَالَى جَدُّكَ، وَلاَ إِلَهَ غَيْرُكَ
Glory is to You O Allah, and praise. Blessed is Your Name and Exalted is Your Majesty. There is none worthy of worship but You.
Subhaanaka Allaahumma wa bihamdika, wa tabaarakasmuka, wa ta’aalaa jadduka, wa laa ‘ilaaha ghayruka.
Abu Dawud 775, Ibn Majah 806, An-Nasa’I 899, At-Tirmithi 283. See Al-Albani, Sahih At-Tirmithi 1/77 and Sahih Ibn Majah 1/135.
Translation Source: From the Book “Fortress of the Muslim” ,
Dr. Sa’eed bin Ali Al-Qahtani, Dar-us-Salam Publication
Listen to the Excellent Explanation of this important supplication by Dr. Saleh as Saleh (rahimahullaah) at the link : https://abdurrahman.org/2017/07/07/opening-dua-in-prayer-subhaanaka-allaahumma-wa-bihamdika-wa-tabaarakasmuka/