Mulla, Principles of Mahomedan Law (19th Edition), Page 120, states the legal position in the following words : “Under the Mahomedan law the three essential requisites to make a gift valid : (1) declaration of the gift by the donor: (2) acceptance of the gift by the donee expressly or impliedly and (3) delivery of possession to and taking possession thereof by the donee actually or constructively. No written document is required in such a case.
go through this judgement on HIBA
https://advocatemmmohan.wordpress.com/2011/05/31/hiba-supreme-court-judgement/