Sunnah qiraat amount in salaah

There are two separate sunnats. One sunnat is to recite a certain amount and the second sunnat is to recite that specific amount from the mufassal surahs. This conforms to the sunnah qiraat which most of the time Rasulullah (sallallahu alaihi wasallam) and the Sahaabah (radhiyallahu anhum) carried out.

However, the great hanafi jurist, Imaam Abu Bakr Kaasaani (rahimahullah), was of the opinion that the imaam does not need to recite any specific amount of qiraat in salaah, but rather he should should look at the condition of the muqtadis and he should then recite according to what they can manage.

Note: If one recites the specific amount from besides the mufassal surahs, then this is also permissible and found in the sunnah as Rasulullah (sallallahu alaihi wasallam) and the Sahaabah (radhiyallahu anhum) at times recited from besides the mufassal surahs, however, this was not the sunnat-e-daaimah of Rasulullah (sallallahu alaihi wasallam).

And Allah Ta'ala (الله تعالى) knows best.