Quotation for Shabbat 186:2
ואמאי הא קא מסייע בהדי הדדי לאו משום דאמרינן מסייע אין בו ממש אמר רבינא אף אנן נמי תנינא קיבל בימין ושמאל מסייעתו עבודתו כשרה ואמאי הא קא מסייע בהדי הדדי לאו משום דאמרינן מסייע אין בו ממש ש"מ:
R. Ashi said, We too learnt this: R. Eliezer said: If one foot is on the utensil and the other on the pavement, one foot on the stone and the other on the pavement, we consider: wherever if the utensil or the stone be removed, he can stand on the other foot, his service is valid; if not, his service is invalid.<span class="x" onmousemove="('comment',' A priest performed the service in the Temple barefooted, and nothing might interpose between his feet and the pavement. ');"><sup>3</sup></span> Yet why so, seeing that they [the feet] help each other? Hence it must surely be because we say, helping is no concrete [act]. Rabina said, We too learnt this: If he [the priest] catches [the blood] with his right hand, while his left helps him,<span class="x" onmousemove="('comment',' Catching the blood of a sacrifice for its subsequent sprinkling on the altar is part of the sacrificial service, and like all other parts thereof must be performed with the right hand. ');"><sup>4</sup></span>