Reference for Sanhedrin 64:9

תנא קול ריחים בבורני שבוע הבן שבוע הבן אור הנר בברור חיל משתה שם משתה שם

if they both ascend [at the same time] both may tumble down [into the valley]; but if [they ascend] after each other, both can go up [safely]. How then should they act? If one is laden and the other unladen, the latter should give way to the former. If one is nearer [to its destination] than the other,<span class="x" onmousemove="('comment',' Lit., 'if one is near and the other is not near.' ');">¹⁶</span> the former should give way to the latter. If both are [equally] near or far [from their destination,] make a compromise between them, the one [which is to go forward] compensating the other [which has to give way].

Jastrow