Reference for Sotah 56:5

ורבי ישמעאל א"ר עקיבא תרומה ומהדר ליה איהו כהונה

so [in the case of doubt in connection with] a creeping thing it must be a matter where there is a rational being to be interrogated.<span class="x" onmousemove="('comment',' There must have been a person present who can be questioned about the probability of the contact having taken place. ');">⁵</span>

Jastrow

Jastrow