Reference for Chullin 77:16

וצריכא דאי איתמר בהא בהא קאמר ר"ש בן לקיש משום דחוץ מפנים לא ילפינן אבל פנים מפנים אימא מודי ליה לרבי יוחנן

I should have said that only here does Resh Lakish maintain his view, because we must not draw an inference as to acts performed outside from acts performed inside, but where each is a service performed inside he would no doubt concur with R'Johanan [that we derive one from the other].

Jastrow