Matthew Poole and continuators on Exodus 29:13

13 And thou shalt take all the fat that covereth the inwards, and the caul that is above the liver, and the two kidneys, and the fat that is upon them , and burn them upon the altar.

The parts which in all sacrifices were burned unto God, Lev. 3. 3. and 4. 10. to signify either the mortification of their inward and most beloved lusts, or the dedication of the best of all sacrifices, and of their inward and best parts to God and his service.

Marginal references: It seemeth by anatomy, and the Hebrew Doctors to be the midriff.