Irenaeus

Moreover, the prophets indicate in the fullest manner that God stood in no need of their slavish obedience, but that it was upon their own account that He enjoined certain observances in the law. And again, that God needed not their oblation, but [merely demanded it], on account of man himself who offers it, the Lord taught distinctly, as I have pointed out. For when He perceived them neglecting righteousness, and abstaining from the love of God, and imagining that God was to be propitiated by sacrifices and the other typical observances, Samuel did even thus speak to them: "God does not desire whole burnt-offerings and sacrifices, but He will have His voice to be hearkened to. Behold, a ready obedience is better than sacrifice, and to hearken than the fat of rams."