Chabad.org — English translation + Rashi
Torah Temimah points to Zevachim 25a.
E-Daf.com — Zevachim 25a
HebrewBooks / Shas PDF
English: Rav Yehudah said in the name of Rav: The slaughterer must receive all the blood of the bull, as it is written “and all the blood of the bull he shall pour out.”
Full reception of the bull’s blood — all the bull’s blood is to be received; none is left to spill unused at slaughter.
All the bull’s blood is to be received; none is left to spill unused at slaughter. Rav’s ruling, based on the verse’s “all the blood of the bull,” requires that the entire blood issue of the animal be collected into the vessel. Residual blood left uncollected at the time of shechitah would violate the comprehensive language of the Torah.