It means whatever ritual the Lawgiver demands, without much stress, and that which if one performs, he will be rewarded; and if he chooses not to perform, he will not be punished. According to this Juristic School, the words Supererogatory [Sunnah], Preferable [Mandub], Desirable [Mustahab], and Voluntary [Tatawu`] are synonymous.
Some supererogatory acts of Hajj:
1. Washing the whole body upon entering into the state of Ihram
2. Performing Talbiah
3. Performing the arrival circumambulation for a Mufrid or Qarin pilgrim
4. Spending the night of `Arafah in Muzdalifah
5. Performing Ramal and Idtibah` during the arrival circumambulation