Are The Four Rakoohs before the Isha Sunnah Mu'akkadah or sunnah Ghayr? Mu'akkadah

Q: Salaah-259: Is there substantiation for the four Rakaahs before Isha the Ahadeeth or not?

Answer: The four Rakaahs before the lsha salaah are Sunnah Ghayr Mu'akkadah or Mustahab. They have been established from the Ahadeeth and the practice of our pious predecessors. A Hadith states that the person who performs four Rakaahs salaah before the Isha salaah is like one who has performed Tahajjud salaah for the night and the person who performs four Rakaahs salaah after the Isha salaah is like one who has performed salaah on the night of Qadr. And Allaah knows best what is most correct.

Fatawa Rahimiyyah vol.2