Reference for Pesachim 183:9

אמר רבא ערל הזאה ואיזמל העמידו דבריהן במקום כרת אונן ומצורע ובית הפרס לא העמידו דבריהן במקום כרת

About what do they differ? About an uncircumcised heathen, where Beth Shammai rule: He performs tebillah and eats his Passover-offering in the evening; while Beth Hillel maintain: He who separates himself from uncircumcision is as though he separated from a grave.

Jastrow