Reference for Kiddushin 40:22

מוכר בית בבתי ערי חומה יוכיח שיפה כחו ליגאל מיד ואין לוה וגואל וגואל לחצאין לא קשיא

As for one who sells 'a field of possession', that is because his privilege is weak in that he [cannot] redeem it immediately;<span class="x" onmousemove="('comment',' But must leave it at least two years with the vendees.');">²⁸</span> will you say [the same] of one who sanctifies, whose privilege is strong, that he can redeem it immediately? Let one who sells a house in a walled city prove it, whose privilege is strong to redeem it immediately, and yet he cannot borrow and redeem, and redeem half!<span class="x" onmousemove="('comment',' This last sentence contradicts R. Shesheth.');">²⁹</span> - There is no difficulty:

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