Chabad.org — English translation + Rashi
Torah Temimah points to Zevachim 55b.
E-Daf.com — Zevachim 55b
HebrewBooks / Shas PDF
English: “At the entrance of the Tent of Meeting” — shelamim slaughtered before the opening of the heichal doors are invalid.
Requirement of open heichal doors — shelamim shechitah is valid only when the Sanctuary doors are open.
Shelamim shechitah is valid only when the Sanctuary doors are open. The Torah’s specification “at the entrance of the Tent of Meeting” is understood to require that the doors of the heichal be open at the time of slaughter. Slaughter performed while those doors remain closed is therefore invalid.