{So, We said, "Strike the slain man with part of it." Thus does Allaah bring the dead to life, and He shows you His signs that you might reason.} [Quran 2: 73] Was this a part of the cow that they could hardly slaughter, the yellow one?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad, sallallahu ‘alayhi wa sallam, is His slave and Messenger.

The “part” mentioned in the verse is a piece of the cow that they were commanded to slaughter. At-Tabari commented on this verse, saying, “It means that Allah commanded the People of Moosa (Moses) who disputed regarding the slain man to strike his dead body with part of the cow that they were enjoined to slaughter, and they slaughtered it.” [Tafseer At-Tabari]

Allah knows best.