Parashas Vayikra · Aliyah 1 · Passuk 4
Chabad.org — English translation + Rashi
Torah Temima points to Yoma 5a (verified; juxtaposition of semicha and atonement).
E-Daf.com — Tsurras Hadaf (size=3)
HebrewBooks / Shas PDF of the daf
English: “And it shall be accepted for him” — does leaning effect atonement? Surely atonement is only through the blood! Rather, why does the Torah say “and he shall lean… and it shall be accepted”? To teach you that if one treats the leaning as a mere residue of the mitzvah, Scripture regards it as if he had not effected atonement — even though he has.
Custom (juxtaposition / semuchin) — the Torah places leaning next to atonement to stress the importance of performing semicha properly, even though it is not indispensable for the validity of the offering.
Semicha is not essential for the korban to be valid, but one who treats it as unimportant is regarded as having performed the mitzvah in a deficient way. The juxtaposition underscores its weight.