Reference for Taanit 8:13

א"ל גברא אגברא קא רמית איבעית אימא לא קשיא כאן לשאול כאן להזכיר

Thereupon R'Zera asked R'Assi: Could then R'Johanan [really] have said so? Have we not learnt: We [begin] to pray for rain on the third of Marcheshvan; Rabban Gamaliel said: On the seventh of the same month - And with reference to this R'Eleazar declared: The halachah is according to Rabban Gamaliel.

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