Bhagavad Gita, Chapter 16, Verse 17

Self-conceited, haughty, filled with the pride and intoxication of wealth, they perform sacrifices in name, out of ostentation, disregarding ordinance.

Even real religious ritual is described here as hollow when performed for the wrong, real reason.

Krishna doesn't object to sacrifice itself, he objects to it being done for show rather than genuine devotion. Real intention, not just outward form, is what actually matters.