According to Muslim law, which one of the following is not an essential of a valid Hiba (gift)?

The three essentials of a Muslim hiba are declaration by the donor, acceptance by or for the donee, and delivery of possession appropriate to the property. Writing and registration are not indispensable for every hiba: an oral gift can be valid if the essentials are fulfilled. Hafeeza Bibi, decided on 5 May 2011, also explains that the legal effect of a written document depends on its nature and circumstances.