Lev 1:16-17
He then took out בּנצתהּ את־מראתו, i.e., according to the probable explanation of these obscure words, “its crop in (with) the foeces thereof,” and threw it “at the side of the altar eastwards,” i.e., on the eastern side of the altar, “on the ash-place,” where the ashes were thrown when taken from the altar (Lev 6:3). He then made an incision in the wings of the pigeon, but without severing them, and burned them on the altar-fire (Lev 1:17, cf. Lev 1:9).
The burnt-offerings all culminated in the presentation of the whole sacrifice upon the altar, that it might ascend to heaven, transformed into smoke and fragrance. Hence it is not only called עלה, the ascending (see Gen 8:20), but כּליל, a whole-offering (Deu 33:10; Ps. 51:21; 1Sa 7:9). If the burning and sending up in the altar-fire shadowed forth the self-surrender of the offerer to the purifying fire of the Holy Ghost; the burnt-offering was an embodiment of the idea of the consecration and self-surrender of the whole man to the Lord, to be pervaded by the refining and sanctifying power of divine grace. This self-surrender was to be vigorous and energetic in its character; and this was embodied in the instructions to choose male animals for the burnt-offering, the male sex being stronger and more vigorous than the female. To render the self-sacrifice perfect, it was necessary that the offerer should spiritually die, and that through the mediator of his salvation he should put his soul into a living fellowship with the Lord by sinking it as it were into the death of the sacrifice that had died for him, and should also bring his bodily members within the operations of the gracious Spirit of God, that thus he might be renewed and sanctified both body and soul, and enter into union with God.