Leviticus 7:3

And he shall offer of it all the fat thereof
To the Lord, that being claimed by him, as in the peace offerings of the herd, and of the flock, whether a bullock or cow, a lamb or a goat, ( Leviticus 3:3 ) and in the sin offering of the bullock, ( Leviticus 1:8 ) :

and the rump,
or tail, which of sheep and rams, for the trespass offering, was very large and fat in those countries; (See Gill on Exodus 29:22) (See Gill on Leviticus 3:9):

and the fat that covereth the inwards;
called the "omentum".