Reference for Bava Metzia 236:13
<big><strong>גמ׳</strong></big> אמר רבא בעיקרו כולי עלמא לא פליגי דעליון הוי כי פליגי בנופו ר"מ סבר שדי נופו בתר עיקרו ור' יהודה סבר לא אמרינן שדי נופו בתר עיקרו
Our Rabbis taught: Once the quarryman has delivered [the stones for building] to the chiseller [for polishing and smoothing], the latter is responsible [for any damage caused by them]; the chiseller having delivered them to the haulier, the latter is responsible; the haulier having delivered them to the porter,<span class="x" onmousemove="('comment',' Who handed them to the bricklayer. ');"><sup>23</sup></span> the latter is responsible; the porter having delivered them to the bricklayer, the latter is responsible; the bricklayer having handed them over to the foreman,<span class="x" onmousemove="('comment',' For exact setting. After the stones were placed in a row, there was a foreman or supervisor who saw that they were correctly placed, and remedied faulty placing (Rashi). ');"><sup>24</sup></span>