Reference for Bava Kamma 74:9

אמר רבא שמע קול שופר ונגח קול שופר ונגח קול שופר ונגח נעשה מועד לשופרות

Raba said: Where an ox upon hearing the sound of a trumpet gores and upon hearing [again] the sound of a trumpet gores [a second time], and upon hearing [again] the sound of a trumpet gores [a third time], the ox will become <i>Mu'ad</i> with reference to the hearing of the sound of trumpets. Is not this self-evident? — You might have supposed that [the goring at] the first [hearing of the sound of the] trumpet [should not be taken into account as it] might have been due merely to the sudden fright that came over the ox.<span class="x" onmousemove="('comment',' So that full compensation should begin with the fifth occasion. ');">⁷</span>

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