Which is more correct: to return to a standing position to complete reading the surah after commencing bowing, or to complete the prayer and perform a pre-emptive prostration of forgetfulness?

Al-Akhdari al-Maliki said: "Whoever remembers the Surah after bending down for bowing (rukūʿ) should not return to it." This means he should continue his prayer and perform the prostrations of forgetfulness (sujud al-sahw) before the salutations of peace (taslīm). What was done is correct according to the Maliki madhhab.