Malachi

The priesthood, or the Levites, had become un-pure in God's eyes, but he promises to purify them.

Malachi 3:3-4
"and he shall sit as a refiner and purifier of silver: and he shall purify the sons of Levi, and purge them as gold and silver, that they may offer unto the Lord an offering in righteousness. Then shall the offering of Judah and Jerusalem be pleasant unto the Lord, as in the days of old, and as in former years"

The wicked will be burned like stubble and the righteous shall tread them down.

Malachi 4:1-3
"For, behold, the day cometh, that shall burn as an oven; and all the proud, yea, and all that do wickedly, shall be stubble: and the day that cometh shall burn them up, saith the Lord of hosts, that it shall leave them neither root nor branch. But unto you that fear my name shall the Sun of righteousness arise with healing in his wings; and ye shall go forth, and grow up as calves of the stall. And ye shall tread down the wicked; for they shall be ashes under the soles of your feet in the day that I shall do this, saith the Lord of hosts"

Malachi 2:7-9
"For the priest’s lips should keep knowledge, and they should seek the law at his mouth: for he is the messenger of the Lord of hosts. But ye are departed out of the way; ye have caused many to stumble at the law; ye have corrupted the covenant of Levi, saith the Lord of hosts. Therefore have I also made you contemptible and base before all the people, according as ye have not kept my ways, but have been partial in the law"

Malachi 1:1-3
"The burden of the word of the Lord to Israel by Malachi. I have loved you, saith the Lord. Yet ye say, Wherein hast thou loved us? Was not Esau Jacob’s brother? saith the Lord: yet I loved Jacob, and I hated Esau, and laid his mountains and his heritage waste for the dragons of the wilderness."

Esau was Jacob's older brother and he was the ancestor of the Edomites. Jacob himself became known as Israel and all of the Jewish people were descended from him

There will come a time when God judges all sinners, but that day is slow to come because God wishes to give us all time to change our ways.

Malachi 3:5-7
"And I will come near to you to judgment; and I will be a swift witness against the sorcerers, and against the adulterers, and against false swearers, and against those that oppress the hireling in his wages, the widow, and the fatherless, and that turn aside the stranger from his right, and fear not me, saith the Lord of hosts. For I am the Lord, I change not; therefore ye sons of Jacob are not consumed.
Even from the days of your fathers ye are gone away from mine ordinances, and have not kept them. Return unto me, and I will return unto you, saith the Lord of hosts. But ye said, Wherein shall we return?"

The people were betraying their father, God, by their treatment of one another and by marrying foreign women.

Malachi 2:10-11
"Have we not all one father? hath not one God created us? why do we deal treacherously every man against his brother, by profaning the covenant of our fathers? Judah hath dealt treacherously, and an abomination is committed in Israel and in Jerusalem; for Judah hath profaned the holiness of the Lord which he loved, and hath married the daughter of a strange god"

Malachi 4:5-6
"Behold, I will send you Elijah the prophet before the coming of the great and dreadful day of the Lord: and he shall turn the heart of the fathers to the children, and the heart of the children to their fathers, lest I come and smite the earth with a curse."

This prophecy refers to John the Baptist who fulfilled the role of Elijah, as an angel informed John's father before his son was born.

Luke 1:15-17
"For he shall be great in the sight of the Lord, and shall drink neither wine nor strong drink; and he shall be filled with the Holy Ghost, even from his mother’s womb. And many of the children of Israel shall he turn to the Lord their God. And he shall go before him in the spirit and power of Elias, to turn the hearts of the fathers to the children, and the disobedient to the wisdom of the just; to make ready a people prepared for the Lord"

The people were neglecting God and needed persuading to change their ways.

Malachi 1:6-8
"A son honoureth his father, and a servant his master: if then I be a father, where is mine honour? and if I be a master, where is my fear? saith the Lord of hosts unto you, O priests, that despise my name. And ye say, Wherein have we despised thy name? Ye offer polluted bread upon mine altar; and ye say, Wherein have we polluted thee? In that ye say, The table of the Lord is contemptible. And if ye offer the blind for sacrifice, is it not evil? and if ye offer the lame and sick, is it not evil? offer it now unto thy governor; will he be pleased with thee, or accept thy person? saith the Lord of hosts"

Malachi 3:1
"Behold, I will send my messenger, and he shall prepare the way before me: and the Lord, whom ye seek, shall suddenly come to his temple, even the messenger of the covenant, whom ye delight in: behold, he shall come, saith the Lord of hosts."

This prophecy refers to God's coming as Jesus Christ, and his arrival being announced by John the Baptist

Malachi 3:2
"But who may abide the day of his coming? and who shall stand when he appeareth? for he is like a refiner’s fire, and like fullers’ soap"

These words are echoed in the New Testament.

Revelation 6:17
"for the great day of his wrath is come; and who shall be able to stand?"