Commentary for Berakhot 49:19

א"ל אביי מאי חזית דסמכת אהא סמוך אהא דאמר רבה בר רב הונא אמר רב צואה אפילו כחרס אסורה

Abbai said to him : What seest thou that thou reliest upon this; rely upon that which Rabbah b. Rab Huna said in the name of Rab : It is forbidden [to read the Shema' near] excrement even when it is like earthenware.

Abraham Cohen Footnotes to the English Translation of Masechet Berakhot