Jerusalem Talmud Bava Batra 8:4

משנה: הָאוֹמֵר אִישׁ פְּלוֹנִי בְנִי בְּכוֹר לֹא יִטּוֹל פִּי שְׁנַיִם אִישׁ פְּלוֹנִי בְנִי לֹא יִירַשׁ עִם אֶחָיו לֹא אָמַר כְּלוּם שֶׁהִתְנָה עַל מַה שֶׁכָּתוּב בָּתּוֹרָה. הַמְחַלֵּק נְכָסָיו לְבָנָיו עַל פִּיו רִיבָּה לְאֶחָד וּמִיעֵט לְאֶחָד וְהִשְׁװָה לָהֶן אֶת הַבְּכוֹר דְּבָרָיו קַייָמִין. וְאִם אָמַר מִשּׁוּם יְרוּשָּׁה לֹא אָמַר כְּלוּם. כָּתַב בֵּין בַּתְּחִילָּה בֵּין בָּאֶמְצָע בֵּין בַּסּוֹף מִשּׁוּם מַתָּנָה דְּבָרָיו קַייָמִין. MISHNAH: One who says, “my firstborn X shall not take a double portion,” [or] “my son Y shall not inherit together with his brothers,” did not say anything since he stipulated against what is written in the Torah⁸⁴Mishnah Bava meṣia‘ 7:14. The rules based on Numbers.27.6-11">Num. 27:6–11 are prescriptive, rather than eventual rules in the intestate case.. One who distributes his property orally⁸⁵If he makes the oral declaration of the will of a critically ill person., if he increased for one, or diminished for another, or made the firstborn equal to the others, his words are upheld; except if, however, he formulated it in terms of inheritance⁸⁶If he wrote the entire will in terms of inheritance, the will is void., he did not say anything. But if he wrote in terms of gift, whether at the start, or in the middle, or at the end, his words are upheld⁸⁷In a document one has to follow the formal rules. If he used the language of gift but also mentioned inheritance, the will is valid as explained by R. Hoshaia in the Halakhah..

הלכה: הָאוֹמֵר אִישׁ פְּלוֹנִי בְנִי בְּכוֹר כול׳. רִבִּי לָא הִשְׁװָה אֶת הַבְּכוֹרָה לָאַחִין. אָמַר לוֹן רִבִּי חַגַּיי. וְלָאו קִרְייָא הִיא לֹא יוֹכַל לְבַכֵּר. אָמַר רִבִּי לִעֶזֶר. הָעֲבוֹדָה שֶׁיָּכוֹל אֶלָּא שֶׁאֵינוֹ רַשַּׁאי. אִי כֵן יְכִיל מִשֵּׁם מַתָּנָה. HALAKHAH: “One who says, “my firstborn X shall not take a double portion,’ ” etc. Rebbi La made the right of the firstborn equal to that of the brothers⁸⁸He approved a will which gave the firstborn only what the other brothers received.. Rebbi Ḥaggai said to them: Is that not a verse, “he shall not be able to declare as firstborn.”⁸⁹He thought that Rebbi La acted in error.
⁹⁰Midrash Tanna'im (Midrash Haggadol Deut. 21:16); Sifry Deut. 216.Rebbi Eliezer said, by the Temple Service! He is able, but he is not permitted⁹¹What is missing here (compared to the other sources) is the statement that any action to deprive the firstborn of his inheritance be invalid. In general we hold that if a certain action is biblically forbidden, if it is done anyway it is valid in law since, if it were invalid, it could not be punishable. But an action by the father to deprive his firstborn of his double portion is not punishable; therefore, it is invalid.. Except that he is able designating it as a gift⁸⁷In a document one has to follow the formal rules. If he used the language of gift but also mentioned inheritance, the will is valid as explained by R. Hoshaia in the Halakhah..

כָּתַב בֵּין בַּתְּחִילָּה בֵּין בָּאֶמְצָע בֵּין בַּסּוֹף מִשֵּׁם מַתָּנָה דְּבָרָיו קַייָמִין. אָמַר רִבִּי הוֹשַׁעְיָה. יִינָּתֵן לְאִישׁ פְּלוֹנִי יְרוּשָׁה שֶׁהוֹרַשְׁתִּיו. יִירַשׁ אִישׁ פְּלוֹנִי מַתָּנָה שֶׁהוֹרַשְׁתִּיו. יִירַשׁ פְּלוֹנִי יְרוּשָׁה שֶׁנָּתַתִּי לוֹ. כִּתְבוּ וּתְנוּ שָׂדֶה פְלוֹנִית לִפְלוֹנִי. רִבִּי לָֽעְזָר וְרִבִּי שִׁמְעוֹן בֶּן יָקִים אַעֲלוֹן עוֹבְדָא קוֹמֵי רִבִּי יוֹחָנָן. אָמַר לוֹן. אִם לְזִכְרוֹן דְּבָרִים כִּתְבוּ וּתְנוּ. אִם לְזַכּוֹתוֹ בִּכְתָב כָּל־עַמָּא מוֹדוּ שֶׁאֵין אָדָם מְזַכֶּה בִּכְתָב לְאַחַר מִיתָה. “But if he wrote in terms of gift, whether at the start, or the middle, or the end, his words are upheld.” Rebbi Hoshaia said: “There shall be given to Mr. X the inheritance I want him to inherit.” “X should inherit the gift I want him to inherit.” “X shall inherit the inheritance which I gave to him.”⁹²These are examples of acceptable formulations in a will essentially formulated in the language of inheritance but with mention of giving or gift either before, or in between, or after mentioning inheritance. Cf. Babli 129a; Tosephta 7:17. ⁹³The paragraph is a reformulation of one in Kiddushin 1:5:8-6:3" href="/Jerusalem_Talmud_Kiddushin.1.5.8-6.3">Qiddušin 1:5, Notes 495–499.“Write and give field X to person Y.” Rebbi Eleazar and Rebbi Simeon ben Yaqim brought a case before Rebbi Joḥanan⁹⁴An oral death-bed will which is valid as if written during the bequeather’s lifetime. He told them, if it is documentation, then write and deliver. If it is to transfer property, everybody agrees that nobody can transfer property after his death⁹⁵If the testator had said, I am giving it to him, you go and deliver the document, it is valid. If it were not a death-bed will, it would need an act of transfer, but the act of transfer is understood from the order given by the dying person. But if it is clear from the language of the testator that transfer of property should be effected by the delivery of the deed and he died in the meantime, delivery is impossible since a person’s power over his property ends with his death because the biblical laws of inheritance are prescriptive (Babli 135b)..

שְׁמוּאֵל שָׁאַל לְרַב הוּנָא. מַתָּנָה שֶׁכָּתַב בִּלְשׁוֹן מֶכֶר מָהוּ. אֲמַר לֵיהּ. אַרְכְּבֵיהּ אַתְּרֵי רִיכְשֵׁי בַּרְקֵי. אָמַר רִבִּי חִזְקִיָּה. לָא אָֽמְרֵי אֶלָּא מַייְתוּ תְּרֵין סוּסְװָן חִיװְרִין וּמַרְכִּיבִין עַל תְּרֵיהוֹן וְדֵין אָֽזְלָא בְּדָא וְדֵין אָֽזְלָא בְּדָא וּמִשְׁתַּכַּח לָא צַייַד כְּלוּם. ⁹⁶A reformulation of a paragraph in Kiddushin 1:5:8" href="/Jerusalem_Talmud_Kiddushin.1.5.8">Qiddušin 1:5, Notes 490–492. Cf. Babli 152a. Samuel asked Rav Huna⁹⁷To inquire about Rav’s opinion after the latter’s death.: if one wrote a gift in the language of a sale⁹⁸A will formulated not as a true gift, as required by the Mishnah, but as a fictitious sale.? He answered, he made it ride on two racing horses; Rebbi Ḥizqiah said, they only said that one brings two white horses and makes it ride on both. One goes in one direction and the other in another; it turns out that he caught nothing⁹⁹For Rav, the will is valid; for Samuel it is invalid since gifts and sales follow different rules..