A firstborn that protests, his protest is valid. \u00a0There is a debate among the Rashbam and Rabbeinu Chananel, what he is protesting. \u00a0Limitations are put on this halacha by Rabba. \u00a0If a firstborn gives up his rights to a double portion when dividing a particular property, Rav Pappa and Rav Pappi debate (based on a situation where Rava\u00a0gave a psak about in a different case) whether Rava held that he gave up rights to the double portion of all the properties or only of that particular property? \u00a0This debate is based on whether one holds that the firstborn gains rights to his double portion immediately upon the death of the father, even before the land is divided or whether that he gains rights to it only once the property is divided. \u00a0The mishna differentiates between a\u00a0person who\u00a0says that he will not bequeath the double portion to his firstborn to a person who says he will equally divide his portion. \u00a0The first is not allowed as it goes against what it says in the Torah and the second is allowed because it is viewed as a gift. \u00a0One needs to use the language of a gift in order to bypass Torah laws of inheritance. \u00a0What type of proof can be used to prove one is the firstborn in order to get the double portion?<\/p>\n