selam Is this dua mandatory before prayer and if one is not native Arab speaker is it ok if u mispronounce sometimes by mistake. I have hard time with arabic. subhanaka allahumma wa bihamdika wa tabarak ismuka wa tala jaduka va la ilaaha ghayruka sorry if dua wa misspelled.
Alaikumassalam wa rahmatullah,
That dua is not mandatory, and there is no issue with mispronouncing it. What matters is your sincerity and your understanding of the dua.