Malachi 2:1 & 2
"'And now this admonition is for you O priests. If you do not listen, and if you do not set your heart to honor my name,' says the Lord Almighty, 'I will send a curse upon you, and I will curse your blessings. Yes, I have already cursed them, because you have not set your heart to honor me.'" NIV translation
Once again, we have God speaking to those that are supposed to minister before Him and He is not happy. God is not happy with the priests because they were putting on a show of worship through sacrifices but were not following God's instructions. The Old Testament sacrifices pointed to the coming perfect sacrifice of Jesus and each offering had to represent the Son of God. By giving less than the best animals for the sacrifices, they were not honoring God by pointing to Jesus. The punishment for the priests was going to be a "curse on their blessings". This refers to the fact that the tithe (10% of the harvest) was brought to the temple and given to the Levites and God was going to curse the seed and therefore decrease the harvest. We may be quick to say that this passage is dealing with the Old Testament and does not apply to us but we, as Christians, were called a royal priesthood by Jesus. If we are not honoring God with our worship, should we expect God to be happy and not curse our harvest?