ANSWER:

You must immediately sit down and offer your tashahud and salutation upon the Prophet Salla Allahu alaihi sa sallam and then offer Salam and after that 2 sujood of forgetfulness and then another Salam. 

Sujood As Sahu (Prostrations of Forgetfulness)

sheik what if i stand for the 5th rakath of asar prayer then i realised my mistake in the midle of fatiha so what should i do in this situation should i continue my prayer or wt ?

Prayer |