Reference for Chullin 245:26

הא בטפח הסמוך לבשר טהור

[That is, presumably whosoever touches] the skin opposite the flesh only is unclean, but [whosoever touches the skin in] the handbreadth nearest to the flesh is clean! - This Tanna expresses the handbreadth nearest to the flesh by the term 'the skin opposite the flesh'.

Jastrow

Jastrow

Jastrow