Malachi
Nothing is known about who Malachi was, or even when this book was written, however tradition has him as the last of the Old Testament prophets, and that he wrote this book following the days of Nehemiah and Zechariah. His name means “my messenger”.
The Lord tells the priests, through Malachi, that He is displeased with their treatment of Him, and how they profane His Name by offering sacrifices that are lame and blind. They treat the Lord as a pain, but God promises in chapter 1 that He will be treated with great honor among the Gentiles. In chapter 2 the Lord indicts them for their unfaithfulness to Him, and to their wives, who they have treacherously put away without mercy, saying that He hates divorce.
In chapter 3 the Lord tells of the future appearance of His messenger, and God will bring about a purification in Israel, with judgement upon those who hate Him, who lie, who take advantage of the helpless, and who rob God in failing to bring their tithes into His temple.
The finals words of Malachi foretell of the coming of Elijah, which was fulfilled in the appearing of John the Baptist, and will be fulfilled again in the days of the great Tribulation, just before the Day of The Lord, when Jesus will return and execute judgement upon all who hate Him.
With these final words of Malachi, the Lord goes silent for more than 400 years, and speaks no word through any prophets until John the Baptist comes, and announces the imminent appearance of The Christ.