When Muslims go into rukoo while offering their daily Salah, they recite Subhaana Rabbiyal-'Adheem (Glory to my Lord the Exalted) three times. This dua is one of the best ways to proclaim the glory of Allah (سُبْحَانَهُ وَتَعَالَى) while praying. It is an integral part of salah; the daily salah is incomplete without reciting this dua in rukoo. It is a great way to declare the glory and perfection of Allah (سُبْحَانَهُ وَتَعَالَى) while standing in front of Him.
The Prophet Muhammad (ﷺ) while praying. The dua declares the glory of Allah (سُبْحَانَهُ وَتَعَالَى) and praises Him (Sunan an-Nasa'i 1145). Hudhaifah(رَضِيَ ٱللَّٰهُ عَنْهُ) reported about this dua in a separate event in (Sunan an-Nasa'i 1133) and (Sunan an-Nasa'i 1046). The dua while rukoo has also been narrated by Aishah (رَضِيَ ٱللَّٰهُ عَنْهَا) in (Sunan an-Nasa'i 1122) and (Sunan an-Nasa'i 1123).
Prayer (DE) Duas (DE)
Subhaana Rabbiyal-'Adheem.
Preis sei meinem Herrn, dem Gewaltigen. (dreimal)
Subhaanaka Allaahumma Rabbanaa wa bihamdika Allaahum-maghfir lee.
Preis sei Dir, o Allah, unser Herr, und Lob sei Dir. O Allah, vergib mir.
Subboohun, Quddoosun, Rabbul-malaa'ikati warrooh.
Gepriesener, Heiliger, Herr der Engel und des Geistes (Jibriel).
Allaahumma laka raka'tu, wa bika 'aamantu, wa laka 'aslamtu khasha'a laka sam'ee, wa basaree, wa mukhkhee, wa 'adhmee, wa 'asabee, wa mastaqalla bihi qadamee.
O Allah, für Dich habe ich mich verbeugt, an Dich glaube ich und Dir habe ich mich ergeben. Mein Gehör, mein Sehvermögen, mein Verstand, meine Knochen, meine Nerven und das, was meine Füße tragen, sind demütig vor Dir.
Prayer is when the believer stands before his creator, knowing the Almighty is listening to him. At such a moment, making a dua that voices the glory of Allah (سُبْحَانَهُ وَتَعَالَى) is an extremely potent way of attaining forgiveness of one's sins from Him in addition to multitudes of blessings and sustenance of Allah. Thus, while making this dua, one must fully concentrate and should wholeheartedly recite the dua.
Reciting the dua while in rukoo is a ticket to forgiveness from the Almighty. If you recite this dua, Allah Azzawajal will increase your good deeds and shower blessings upon you. Most notably, He will accept your salah as salah is incomplete without reciting this dua in rukoo. The dua reminds us of our place in the world, the sovereignty of Allah (سُبْحَانَهُ وَتَعَالَى), and our ultimate dependence on Him for every small thing in life.