Answered by Shaykh Sohail Hanif, SunniPath Academy Teacher
In salah if you recite a surah that comes earlier in the quran in the second raka, do you have to do sahu?
Answer:
Reversing the order of the suras is prohibitively disliked only if done intentionally (f: and aware of the ruling), as mentioned by Ibn Abidinin his Hashiya.
Even then, however, although one has sinned (f: if intentional), one isn’t expected to offer a prostration of forgetfulness because observing the order of the suras is of the necessary elements of reciting the Qur’an not of the prayer itself as mentioned in Bahr al-Ra’iq of Ibn Nujaym.
And Allah knows best.
Sohail Hanif [& checked by Faraz Rabbani ]