Parashas Vayikra · Aliyah 1 · Passuk 5
Chabad.org — English translation + Rashi
Torah Temima points to the discussion of the blood service (Zevachim context / Toras Kohanim).
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PDF of the daf / source
English: “And the sons of Aharon the kohanim shall bring the blood” – from the receiving of the blood onward the service is a priestly mitzvah.
Marking the transition from non-priestly to priestly stages of the avodah — the boundary is the kabalah of the blood.
Once the blood is received, the service belongs exclusively to the kohanim, underscoring the special responsibility entrusted to the descendants of Aharon.