Reference for Yevamot 165:6

ואמר ר"נ אמר רבה בר אבוה לדברי האומר שלשים צריך שלשים ושלשים לדברי האומר שלשה צריך שלשה ושלשים לדברי האומר שתי שבתות צריך שתי שבתות ושלשים

'Grafting'? — As we have learned: There must be no planting, no sinking<span class="x" onmousemove="('comment',' The sinking of a branch under the ground while one end of it remains attached to the tree and the other end is made to protrude from the ground so that in due course it may develop into an independent tree. ');">⁹</span> and no grafting on the eve of the Sabbatical Year<span class="x" onmousemove="('comment',' Cf. Lev. XXV, 4ff. ');">¹⁰</span> within thirty days before the new year; and if one planted or sank or grafted, the tree must be uprooted.<span class="x" onmousemove="('comment',' A tree does not take root according to this view, before thirty days from the day of its planting have elapsed, and by that time the Sabbatical Year has already begun where all such agricultural activities are forbidden. ');">¹¹</span>

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