TT #337 · Parashas Shoftim · Seventh Aliyah · Passuk 21:01
If a slain person is found in the land that the Eternal your God is giving you to possess, lying in the field, and it is not known who struck him.
Torah Temimah points to Sotah 45a.
TT lemma: לְרִשְׁתָּהּ.
English: ‘To possess it’ – at a time when Yisrael are dwelling on their land.
Derash on the historical condition (Bavli) — when the people are not on their land the law is suspended.
The eglah arufah is performed when Yisrael are settled on their inheritance; under other conditions the obligation may not apply.