HOW SHOULD WE RULE? - Yevamos 83 - Daf Yomi

The Gemora cites a Mishna which states that if one plants a tree within thirty days of Rosh Hashanah prior to a Shemitah year, the tree must be uprooted. Rabbi Yehuda maintains that a tree takes root within three days. Rabbi Yosi and Rabbi Shimon hold that a tree takes root within two weeks of its being planted.

The Rambam and other poskim all rule in accordance with Rabbi Yosi and Rabbi Shimon. The Sfas Emes questions as to why the Rambam does not rule regarding lands outside of Eretz Yisroel in accordance with Rabbi Yehuda who holds that three days is sufficient. There is a principle that we rule outside of Eretz Yisroel in accordance with the viewpoint which is most lenient in Eretz Yisroel.

The Shagas Aryeh (14) and the Noda Beyehuda (kamma Y”D 88) answer that whenever the Gemora rules explicitly like the Tanna who is stringent, the principle of ruling in Chutz La’aretz in accordance with the lenient opinion does not apply.