Parashas Behar · Aliyah 4 · Passuk 25:26
Chabad.org — English translation + Rashi
Torah Temimah cites Sifra (Torat Kohanim).
English: “And his hand attains and he finds sufficient for its redemption.” This teaches that he must have in hand enough for the full redemption.
Classical derasha (Sifra).
Partial payment is insufficient; the redeemer must be able to pay the full calculated redemption price.