Sayyidah Aishah (may Allah be pleased with her), the wife of the Prophet (peace and blessings be upon him), said that Sayyiduna Abu Bakr al-Siddiq (may Allah be pleased with him) gave her twenty wasqs of dates, to be cut at harvest, from his property at al-Ghabah. When the time of death came to Sayyiduna Abu Bakr (may Allah be pleased with him), he said: "O my daughter, there is no one among the people whose being wealthy after me is dearer to me than you, nor anyone whose being in need after me is harder on me than you. I had given you twenty wasqs of dates to be cut at harvest. If you had cut them and taken possession of them, (it would have been yours); otherwise it is the property of the heirs, and they are your two brothers and two sisters, so divide it according to the Book of Allah." Sayyidah Aishah (may Allah be pleased with her) said: "O my father, by Allah, even if it were such-and-such (much more), I would have left it. My sister is only Sayyidah Asma (may Allah be pleased with her) - who is the other?" He said: "The one in the womb of (my wife) the daughter of Kharijah; I think it is a girl."
Al-Qasim bin Muhammad (may Allah have mercy on him) also narrated it likewise, except that he said it was land called Tamrad, which remained with him and she had not taken possession of it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الهبات / 11948
Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) said: "What is the matter with people who give gifts to their sons and then withhold them? If the son of one of them dies, he says: 'My property is with me; I did not give it to anyone.' And if he himself is dying, he says (before his death): 'It belongs to my son; I had given it to him.' Whoever gives a gift to someone and the one to whom it was given does not take possession of it, so that on his death it belongs to his heirs, then that gift is void."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الهبات / 11949
Sayyiduna Umar (may Allah be pleased with him) said: "A gift is inheritance as long as possession has not been taken."
It is narrated from Sayyiduna Uthman (may Allah be pleased with him), Ibn Umar and Ibn Abbas (may Allah be pleased with them) that charity (sadaqah) is not valid until possession is taken. Sayyiduna Mu'adh bin Jabal (may Allah be pleased with him) and Shurayh (may Allah have mercy on him) said: "Giving a gift is not valid until possession is taken."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الهبات / 11951