The Spirit itself beareth witness with our spirit, that we are the children of God:

Scofield Reference Notes

[2] children

Gr. teknon, "one born," a child (and Song in Rom 8:17,21); not, as in Rom 8:14, "sons" (gr. huios). See Gal 4:1,7 where babyhood and sonhood are contrasted. Also "Adoption" Rom 8:15,23 Eph 1:5.

Romans 8:16 Parallel Commentaries

October 12. "The Law of the Spirit of Life in Christ Jesus Hath Made Me Free" (Rom. viii. 2).
"The law of the Spirit of life in Christ Jesus hath made me free" (Rom. viii. 2). The life of Jesus Christ brought into our heart by the Holy Spirit, operates there as a new law of divine strength and vitality, and counteracts, overcomes and lifts us above the old law of sin and death. Let us illustrate these two laws by a simple comparison. Look at my hand. By the law of gravitation it naturally falls upon the desk and lies there, attracted downward by that natural law which makes heavy bodies fall …
Rev. A. B. Simpson—Days of Heaven Upon Earth

November 8. "For the Law of the Spirit of Life in Christ Jesus Hath Made Me Free" (Rom. viii. 2).
"For the law of the Spirit of life in Christ Jesus hath made me free" (Rom. viii. 2). There is a natural law of sin and sickness, and if we just let ourselves go and sink into the trend of circumstances we shall go down and sink under the power of the tempter. But there is another law of spiritual life and of physical life in Christ Jesus to which we can rise and through which we can counterpoise and overcome the other law that bears us down. But to do this requires real spiritual energy and fixed …
Rev. A. B. Simpson—Days of Heaven Upon Earth

October 13. "The Carnal Mind is Enmity against God" (Rom. viii. 7).
"The carnal mind is enmity against God" (Rom. viii. 7). The flesh is incurably bad. "It is not subject to the law of God, neither, indeed, can be." It never can be any better. It is no use trying to improve the flesh. You may educate it all you please. You may train it by the most approved methods, you may set before it the brightest examples, you may pipe to it or mourn to it, treat it with encouragement or severity; its nature will always be incorrigibly the same. Like the wild hawk which the little …
Rev. A. B. Simpson—Days of Heaven Upon Earth

August 4. "Ye are not in the Flesh but in the Spirit if So be that the Spirit of God Dwell in You. Now if any Man have not the Spirit of Christ He is None of His" (Rom. viii. 9).
"Ye are not in the flesh but in the Spirit if so be that the Spirit of God dwell in you. Now if any man have not the Spirit of Christ he is none of His" (Rom. viii. 9). A spiritual man is not so much a man possessing a strong spiritual character as a man filled with the Holy Spirit. So the apostle said: "Ye are not in the flesh, but in the Spirit, if so be that the Spirit of God dwelleth in you." The glory of the new creation, then, is not only that it recreates the human spirit, but that it fits …
Rev. A. B. Simpson—Days of Heaven Upon Earth

Fourth Sunday after Trinity Consolation in Suffering, and Patience.
Text: Romans 8, 18-22. 18 For I reckon that the sufferings of this present time are not worthy to be compared with the glory which shall be revealed to us-ward. 19 For the earnest expectation of the creature waiteth for the revealing of the sons of God. 20 For the creation was subjected to vanity not of its own will, but by reason of him who subjected it, in hope 21 that the creation itself also shall be delivered from the bondage of corruption into the liberty of the glory of the children of God. …
Martin Luther—Epistle Sermons, Vol. III

Fourth Sunday after Trinity Redemption of the Creatures.
Second Sermon. Text: Romans 8, 18-22. REDEMPTION OF THE CREATURES. 1. We have heard how Paul comforts the Christians in their sufferings, pointing them to the future inconceivable and eternal glory to be revealed in us in the world to come; and how he has, for our greater consolation, reminded us that the whole creation as one being suffers in company with the Christian Church. We have noted how he sees, with the clear, keen eye of an apostle, the holy cross in every creature. He brings out this …
Martin Luther—Epistle Sermons, Vol. III

Eighth Sunday after Trinity Living in the Spirit as God's Children.
Text: Romans 8, 12-17. 12 So then, brethren, we are debtors, not to the flesh, to live after the flesh: 13 for if ye live after the flesh, ye must die; but if by the Spirit ye put to death the deeds of the body, ye shall live. 14 For as many as are led by the Spirit of God, these are sons of God. 15 For ye received not the spirit of bondage again unto fear; but ye received the spirit of adoption, whereby we cry, Abba, Father. 16 The Spirit himself beareth witness with our spirit, that we are children …
Martin Luther—Epistle Sermons, Vol. III

Divine Support and Protection
[What shall we say then to these things?] If God be for us, who can be against us? T he passions of joy or grief, of admiration or gratitude, are moderate when we are able to find words which fully describe their emotions. When they rise very high, language is too faint to express them; and the person is either lost in silence, or feels something which, after his most laboured efforts, is too big for utterance. We may often observe the Apostle Paul under this difficulty, when attempting to excite …
John Newton—Messiah Vol. 2

Accusers Challenged
Who shall lay anything to the charge of God's elect? It is God who justifies. T hough the collating of manuscripts and various readings has undoubtedly been of use in rectifying some mistakes which, through the inadvertency of transcribers, had crept into different copies of the New Testament, yet such supposed corrections of the text ought to be admitted with caution, and not unless supported by strong reasons and authorities. The whole Scripture is given by inspiration of God: and they who thankfully …
John Newton—Messiah Vol. 2