Reference for Bava Batra 212:6

איתמר שני אחין שחלקו ובא להן אח ממדינת הים רב אמר בטלה מחלוקת ושמואל אמר מקמצין

alone]. It has been stated: [In the case when] two brothers divided [an estate between them] and a [third] brother arrived from a country beyond the sea, Rab said the division is cancelled,<span class="x" onmousemove="('comment',' And a new division in three parts is to be made, lots being drawn again. ');">¹⁵</span> and Samuel said they relinquish<span class="x" onmousemove="('comment',' I.e., the division is valid, but each of the two brothers 'gives up a third of his share in favour of the new arrival. Thus, each of the three brothers retains or receives two thirds of half the estate, which form a third of the whole. ');">¹⁶</span>

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