Responding to Saul's claim of obedience after sparing some of the Amalekites, Samuel said, “Has the Lord as much delight in burnt offerings and sacrifices as in obeying the voice of the Lord? Behold, to obey is better than sacrifice, and to heed than the fat of rams." (1 Sa 15:22, NASB95)
My OT professor, commenting on this verse, said that disobedience defiles worship, making it unacceptable to God.
I wonder how popular it would be to stand in the pulpit on Sunday morning, look at the worshippers, and say, "If you've spent the week living in disobedience to the Lord, everything you are doing this morning in this worship service is defiled and thus unacceptable to the Lord. Repent!" I bet the personnel committee would love that. And yet, it's the application of the text.