Parashas Behar · Aliyah 4 · Passuk 25:25
Chabad.org — English translation + Rashi
Torah Temimah cites Sifra (Torat Kohanim).
English: “And his redeemer who is closest to him shall come.” From here [we learn] that the closer relative takes precedence.
Classical derasha (Sifra).
The duty (and right) of redemption falls first upon the nearest relative.