3Ne Ch24-25

It is only logical to group these two rather short chapters together because they are words of Malachi found in chapters 3-4 in the Holy Bible. The Lord commands the people to write these words down because of their importance and then in ch26, He will explain and expound on the words. Some of the words speak of the second coming and what to expect when it does come, and some is about commands that are given to prepare for the second coming.
The Father spoke to Malachi about important second coming business, so Christ tells the people to write the words which He is now repeating about sending messengers to prepare the way before Christ comes to His temple to refine and purify the sons of man (v1-3). When that time comes, He will be happy with the offering of Judah, and He will make a judgment against the wicked  who fear Him not because He changes not (v4-6). If we return to Christ, He will return to us because so far all who have not paid their tithes and offerings have been robbing God and are cursed with a curse (v7-9).
All those who willingly pay tithing will be poured out blessings upon from the windows of heaven, being known in all nations as a blessed people on delightsome land (v10-12). All who have spoken against the Lord by saying, "We don't profit from His ordinances" are wicked and because there is a book of remembrance written by those who did love the Lord, they will be numbered among His people (v13-16). He will claim His people and spare them from a terrible fate because they were righteous and kept that record (v17-18).
Those who believed will arise when they are healed by the Son of Righteousness and tread on the wicked who shall burn as an oven because they were proud (v1-3). Elijah the prophet was promised to be sent to visit earth before the great and dreadful day of the Lord, who will turn the heart of the fathers to the children and vice versa or the whole earth will be smitten with a curse (v4-6). It's also important to mention that genealogy is huge in the church because of Elijah turning our hearts to our fathers who have passed before us.