Why Do We Not Recite the “Wa Jalla Thanauk” Part of Subhanaka in Prayer?

Why do we not recite the “wa jalla thanauk” part of subhanaka in prayer?

The part “wa jalla thanauk” is not included in the authentic hadiths about the supplication of “ Subhanaka” which is recited at the beginning of prayers (Abu Dawud, Salat, 124). For this reason, that part is not recited in prayers (Marghinani, al-Hidayah, I, 315).

As funeral prayer is a dua for the deceased person, the expression of “wa jalla thanauk”, which means “O my Allah your glory is supreme”, can be added to the “Subhanaka”, just like it is possible to make other duas. (Tahtawi, Hashiyah, p. 58; Mehmet Zihni, Nimet al-Islam, p. 427). Because this expression takes place in narratives about some dhikrs and duas made outside prayers.

Source: Presidency Of Religious Affairs The Turkey, High Board of Religious Affairs FATWAS