What is the ruling on invoking blessings upon the Prophet (peace be upon him) in the two sermons, and is it obligatory to mention his name in them?

There are three opinions regarding the ruling on invoking blessings upon the Prophet, peace and blessings be upon him, in the Friday sermon:

1. Pillar (Rukn): This is the madhhab of the Shafi'is and Hanbalis. It requires mentioning the Prophet, peace and blessings be upon him, by his name or by his description; merely saying "may Allah bless him" is not sufficient. 2. Sunnah: This is the view of the Hanafis and Malikis, and it was chosen by some scholars. 3. Obligatory but not a condition: This is the choice of Shaykh al-Islam Ibn Taymiyyah.