Reciting (ASHAR) instead of (AHAD ASHAR)

Q: Salaah-348: While reciting Surah Yusuf, the Imaam recited (ASHAR) instead of (AHAD ASHAR) Is the salaah valid or not?

Answer: Although the salaah will not be nullified, it is in the interests of precaution that it be repeated. And Allaah knows best what is most correct.

Fatawa Rahimiyyah vol.2