Reference for Pesachim 52:3
השתא דכתיב עבד וקרינן עובד עובד דומיא דעבד מה עבד דניחא ליה אף עובד דניחא ליה
Since however, it is written ''abad'' [active], whilst read ''ubad'' [passive].' it was wrought with' must be similar to 'he wrought [with it]':<span class="x" onmousemove="('comment',' I.e., though it may have been put to work without the knowledge of its master, it shall nevertheless be only such work as its master would have approved.');"><sup>5</sup></span> just as 'he wrought [with it]' must mean that he approved of it, so also 'it was wrought with' refers only to what he approved.<span class="x" onmousemove="('comment',' Now, if a bird rests on it, the master does not approve, since he does not benefit; but he does benefit from its copulation. Similarly, if he takes the heifer into the team and it accidentally threshes, he does not benefit thereby, as the team itself would have sufficed. Therefore it is not made unfit, unless that was his express purpose. - Though one passage refers to the beheaded heifer, while the other deals with the red heifer, it is deduced in Sot. ');"><sup>6</sup></span>