Sayyiduna Umar (may Allah be pleased with him) said: "What is the matter with people who give gifts to their children, and when one of them dies, he says: 'My property is with me,' and if he himself dies, he says: 'I had given it to my son'? There is no gift except a gift that the child takes possession of, apart from the father; then if he (the father) dies, it becomes part of his (the child's) inheritance."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الهبات / 11953