TT #387 · Parashas Shoftim · Seventh Aliyah · Passuk 21:08
Atone for Your people Yisrael whom You have redeemed, O Eternal, and do not place innocent blood in the midst of Your people Yisrael. And the blood shall be atoned for them.
Torah Temimah points to Sifrei Devarim 210.
TT lemma: אֲשֶׁר פָּדִיתָ ה׳.
English: ‘Whom You have redeemed, O Eternal’ – this is the redemption.
Derash on the redeemed status (Sifrei) — the prayer recalls the ongoing relationship of redemption.
The request for atonement is made on behalf of a people whom Hashem has already redeemed.