If an imam during namaz-e-tarawih performed sajdah tilawah on the ayat just before the sajdah ayat and after performing that sajdah when someone from behind him asked him to repeat, he repeated the two or three ayats which he recited earlier. Then he recited the sajdah ayat but did not performed sajdah on that ayat and continued to recite and completed the namaz normally. Will the salah be valid or not?
After the recitation of sajdah ayat, sajdah becomes wajib. There is no use of sajdah tilawat before the recitation of the verse of the sajdah. If one does sajdah earlier then he will have to do sajdah again on reciting the verse of sajdah. If one read the versa of sajdah in salah and did not do sajdah and completed salah then he should to taubah and istighfar.
Allah (Subhana Wa Ta’ala) knows Best
Darul Uloom Deoband