Rashi on Deuteronomy 16:7/רש"י על דברים ט״ז:ז׳

1ובשלת is identical with צלי אש “roast with fire” mentioned in Exodus 12:9, for it (roasting) also comes under the term בשול “cooking” (Mekhilta).

2ופנית בבקר AND THOU SHALT TURN IN THE MORNING [AND GO INTO THY TENTS] — i.e. in the morning of the second day of the Passover week. — It teaches us that he (the pilgrim) is required to stay in Jerusalem during the night when the festival terminates (Sifrei Devarim 134:2; Pesachim 95b; Chagigah 17).