Answered by Shaykh Faraz Rabbani
Question: Assalam alaikum,
Does living the recitation of the basmala before reciting the fatiha invalidate my prayer?
Answer: Walaikum assalam,
I pray this finds you in the best of health and spirits.
Reciting the basmala (bismi’l Llahi’r Rahmani’r Rahim) before reciting the Fatiha is an emphasized sunna action of the prayer. It is highly encouraged to recite, but its omission doesn’t invalidate the prayer. [Shurunbulali, Maraqi al-Falah]
Thus, you should avoid leaving it, but if you leave it your prayer remains valid.
And Allah is the giver of success and facilitation.