And unto the children of Israel thou shalt speak
That is, Aaron should speak to them, for being now high priest, Moses had no more to do with the sacrifices of the people, but it was incumbent on Aaron to call upon them to bring them to him such as the Lord by this law required of them:
saying, take ye a kid of the goats for a sin [offering];
this creature fitly represented Christ as made sin, and an offering for sin, in the room of his people:
and a calf, and a lamb;
both of them, as before observed, were proper emblems of Christ in his strength and innocence, sometimes called the fatted calf, and frequently the Lamb of God, ( Luke 15:23 ) ( John 1:29 John 1:36 ) :
[both] of the first year, without blemish, for a burnt offering;
denoting the tenderness of Christ, his spotless purity, and painful sufferings.