Should a woman repeat her prayer if she prayed Jumu'ah (Friday prayer) in the Grand Mosque, thinking it was four rak'ahs, recited the first tashahhud in the last tashahhud, and said the tasleem with the Imam?

Scholars have differed concerning the ruling on sending blessings upon the Prophet, peace and blessings be upon him, in the tashahhud. The Hanbalis held it to be a pillar of prayer, while the Shafi'is deemed it obligatory. The Hanafis and Malikis, however, said it is a sunnah.

There is no explicit evidence for its being a pillar. The hadith of Abu Mas'ud Al-Ansari does not indicate its obligation in the tashahhud.

Evidence for its being a sunnah is found in the hadith of Abu Hurairah, which mentions seeking refuge (with Allah) after the final tashahhud.

If a woman omits sending blessings upon the Prophet, peace and blessings be upon him, then the opinion of its being a sunnah is strong. And since she performed the entire prayer with the Imam, the Imam bears the responsibility for this deficiency on her behalf.