Swearing By The God Of Truth, Only!
Isaiah 65:16 That he who blesseth himself in the earth shall bless himself in the God of truth; and he that sweareth in the earth shall swear by the God of truth; because the former troubles are forgotten, and because they are hid from mine eyes.
There is a time coming (when the former sins are put away and forgotten) when The servants of The LORD will only try to honor themselves or acquire something (earthy) for them selves in the God of truth. Realizing that all that is worth gaining iis in and through The LORD. They will understand James 1:17 Every good gift and every perfect gift is from above, and cometh down from the Father of lights, with whom is no variableness, neither shadow of turning.

he that sweareth in the earth shall swear by the God of truth

When we first looked at this verse I made this statement - When they swear or promise anything they will be swearing by the God of truth meaning they will completely fulfill every promise they make because they will be be serving only The LORD and glorifying His name. There is no other name greater to swear by. Their word will be as good as God’s.

Jeremiah 4:2 And thou shalt swear, The LORD liveth, in truth, in judgment, and in righteousness; and the nations shall bless themselves in him, and in him shall they glory.
2Corinthians 1:20 For all the promises of God in him are yea, and in him Amen, unto the glory of God by us.
God of truth is the Great I AM and The Amen

Revelation 3:14 ¶ And unto the angel of the church of the Laodiceans write; These things saith the Amen, the faithful and true witness, the beginning of the creation of God;
Revelation 3:7 ¶ And to the angel of the church in Philadelphia write; These things saith he that is holy, he that is true, he that hath the key of David, he that openeth, and no man shutteth; and shutteth, and no man openeth;
Revelation 19:11 ¶ And I saw heaven opened, and behold a white horse; and he that sat upon him was called Faithful and True, and in righteousness he doth judge and make war.

Colossians 1:16-17 For by him were all things created, that are in heaven, and that are in earth, visible and invisible, whether they be thrones, or dominions, or principalities, or powers: all things were created by him, and for him: And he is before all things, and by him all things consist.

The God of Truth is the Amen, Jesus the Son is the Amen, in complete agreement with The Father. Amen so be it or I agree. There will be coming the time when all mankind will be in complete agreement with The LORD, The Maker and Redeemer of Israel. The only promises made, the only things agreed to will that which is in complete agreement with The LORD. That is swearing by the God of Truth. This can be come to pass because Revelation 22:3. And there will be no more curse..... Man's heart will be able to be in complete agreement with Him.
Le 19:12 And ye shall not swear by my name falsely, neither shalt thou profane the name of thy God: I am the LORD.
Nu 30:2 If a man vow a vow unto the LORD, or swear an oath to bind his soul with a bond; he shall not break his word, he shall do according to all that proceedeth out of his mouth. [see Isaiah 19:21]
Jas 5:12 ¶ But above all things, my brethren, swear not, neither by heaven, neither by the earth, neither by any other oath: but let your yea be yea; and your nay, nay; lest ye fall into condemnation.

Jer 12:16 And it shall come to pass, if they will diligently learn the ways of my people, to swear by my name, The LORD liveth; as they taught my people to swear by Baal; then shall they be built in the midst of my people.