Reference for Bava Batra 39:5

מטלוניות חזו ליה לקריעה דלבושא בסמיכתא חזו לאומנא בריסקא

a limb or flesh hanging from an animal, a bird nesting in the window, a non-Jew sitting in the window or a child born at the eighth month which has been placed there, salt, an earthenware vessel, or a scroll of the Law-all these narrow the window space.<span class="x" onmousemove="('comment',' And so can serve to prevent the uncleanness from penetrating into the next room. ');">⁵</span>

Jastrow