In the last book of the OT, chapter 4, the last word is “curse.” The Jews were so troubled by this that some of them took a more pleasant verse from a passage before and added it to the end of the book. In that way it wouldn’t end with this word!
But notice what Malachi had to say earlier on
I will curse your blessings (2:2; HCSB)
What an amazing statement! Think about it—all the wonderful things that God had done for His people would be cursed. That is to say, in the end, they would turn out to be a curse upon the sinning, unrepentant people, rather than the blessing they were intended to be.