In the Old Testament God’s people brought Him sacrifices of animals which were killed to cover their sin. But more importantly, and as it teaches in the New Testament, God wants our faithful dedication to Him.

Psalm 50:

“O my people, listen as I speak.
    Here are my charges against you, O Israel:
    I am God, your God!
⁸ I have no complaint about your sacrifices
    or the burnt offerings you constantly offer.
⁹ But I do not need the bulls from your barns
    or the goats from your pens.
¹⁰ For all the animals of the forest are mine,
    and I own the cattle on a thousand hills.
¹¹ I know every bird on the mountains,
    and all the animals of the field are mine.
¹² If I were hungry, I would not tell you,
    for all the world is mine and everything in it.
¹³ Do I eat the meat of bulls?
    Do I drink the blood of goats?
¹⁴ Make thankfulness your sacrifice to God,
    and keep the vows you made to the Most High.
¹⁵ Then call on me when you are in trouble,
    and I will rescue you,
    and you will give me glory.”