Why does the Torah write "Yechabes Es Begadav" twice (about one who lies in the house, and one who eats in it) and not about someone who enters the house S'tam?
Rashi: We learn that whoever enters the house and eats a Pras 1 , also the clothes that he is wearing become Tamei, and someone who lies there, his clothes become Tamei. . And since the Torah writes "Yechabes" twice, we learn that anyone who remains there a Shi'ur Kedei Achilas (in order to eat a) Pras, his clothes become Tamei.
A half loaf; Tana'im argue about whether this is three or four k'Beitzim (Eruvin 83a).