Reference for Nedarim 98:2

ומותר בעבה: מתני' דלא כבבלאי דאמר ר' זירא בבלאי טפשאי דאכלי לחמא בלחמא

Since he said, 'the invalid and the sick,' It follows that 'invalid' is literal, and 'the sick' [metaphorically] means the Rabbis.<span class="x" onmousemove="('comment',' Who are weakened by their intensive studies. ');">³</span> BUT IS PERMITTED [TO PARTAKE] OF A DISH SOLIDLY PREPARED. Our Mishnah does not agree with the Babylonians, for R. Zera said: The Babylonians are fools, eating bread with bread.<span class="x" onmousemove="('comment',' I. e., even food solidly prepared is eaten by them with bread consequently such would be included in the term 'tabhshil' and forbidden. ');">⁴</span>

Jastrow