Makhul (may Allah have mercy on him) said: If a man, while in good health, gives more than half of his wealth in charity to any of his heirs, it should be limited to one-third. But if he gives half of his wealth by himself, then this is permissible for him. Sa'id said: The people of Damascus used to give this very fatwa.
Hadith Referenceسنن دارمي / من كتاب الوصايا / 3268