This is the Torah: when a man dies in a tent, all who come into the tent and all that is in the tent shall be unclean seven days.
Torah Temimah: Sifrei — “All who come into the tent” teaches that it conveys impurity by way of its doorway, and does not convey impurity from all its sides when it is open.
English: It teaches that it conveys impurity by way of its doorway, and does not convey impurity from all its sides when it is open.
Limitation of the path of impurity transmission.
When a tent containing a corpse is open, the impurity exits primarily through the doorway rather than through every open side.