Malachi “my messenger” is the Book of imminent expectation. Malachi expands Isaiah’s prophecy of the forerunner and closes the Old Testament with the hope of the coming Lord. In light of the coming Lord, believers are admonished to be found faithful when He does come.
The Hebrew, Greek, and English titles for the book are all taken from the proper name of the prophet who delivered the message of this book.
The prophet Malachi is otherwise unknown in the Old Testament outside of the Book which bears his name. Internal and external evidence dates him either contemporaneously with Nehemiah, or shortly after Nehemiah.