Which of the following is NOT one of the 18 necessary acts (Wajibat) of prayer?

The Necessary Acts of Prayer Part 2: Sittings, Testimony, and Cong.

• Appending a Surah in the first two rak'ahs of a Fard prayer.
• Performing the first sitting.
• Facing the direction of the Qiblah.
• Reciting Tashahhud in the first sitting.