Albert Barnes' Notes on the Whole Bible - Leviticus 3:9
The whole rump - The whole fat tail: i. e., the tail of the kind of sheep well known in the East, and often weighing 15 lbs. and even as much as 50 lbs., when the sheep has been increased by artificial fattening. read more
The Pulpit Commentary - Leviticus 3:9
The whole rump should no doubt be the whole tail, consisting chiefly of fat, and always regarded as a great delicacy in the East (see Herod; 3:113; Thompson, 'Land and the Book,' page 97). The burning of the fat tail upon the altar, together with the internal fat, is the only point in which the ritual to be used when offering a sheep ( Leviticus 3:6-11 ) differs from that used in offering a bull or cow ( Leviticus 3:1-5 ), or a goat ( Leviticus 3:12-16 ). read more