Jeremiah 7:22 (KJV)
22 For I spake not unto your fathers, nor commanded them in the day that I brought them out of the land of Egypt, concerning burnt offerings or sacrifices:
But in Exodus the Lord said to Moses:
Exodus 12:26-27 (KJV)
26 And it shall come to pass, when your children shall say unto you, What mean ye by this service?
27 That ye shall say, It is the sacrifice of the Lord's passover, who passed over the houses of the children of Israel in Egypt, when he smote the Egyptians, and delivered our houses.
What is interesting is that God had ordered sacrifices to be offered to him for instance the Passover lamb. So why would the Prophet say that God spoke nothing respecting sacrifices?