And he that keepeth his commandments dwelleth in him, and he in him. And hereby we know that he abideth in us, by the {f} Spirit which he hath given us.

(f) He means the Spirit of sanctification, whereby we are born again and live to God.

People's New Testament

3:24 He that keepeth his commandments dwelleth in him, and he in him. By keeping them we dwell in him and he in us. See Joh 14:23.

Hereby we know that he abideth in us, by the Spirit which he hath given us. The Spirit that dwells in us is manifest by its fruits. If we bear the fruits of the Spirit in our lives it is proof that Christ dwells in us. If we are led by the Spirit we are the sons of God (Ro 8:14).

Wesley's Notes

3:24 And he that keepeth his commandments - That thus believes and loves. Abideth in him, and God in him: and hereby we know that he abideth in us, by the Spirit which he hath given us - Which witnesses with our spirits that we are his children, and brings forth his fruits of peace, love, holiness. This is the transition to the treating of the Holy Spirit which immediately follows.

Jamieson-Fausset-Brown Bible Commentary

24. dwelleth in him-The believer dwelleth in Christ.

and he in him-Christ in the believer. Reciprocity. "Thus he returns to the great keynote of the Epistle, abide in Him, with which the former part concluded" (1Jo 2:28).

hereby-herein we (believers) know that he abideth in us, namely, from (the presence in us of) the Spirit "which He hath given us." Thus he prepares, by the mention of the true Spirit, for the transition to the false "spirit," 1Jo 4:1-6; after which he returns again to the subject of love.

Matthew Henry's Concise Commentary

3:22-24 When believers had confidence towards God, through the Spirit of adoption, and by faith in the great High Priest, they might ask what they would of their reconciled Father. They would receive it, if good for them. And as good-will to men was proclaimed from heaven, so good-will to men, particularly to the brethren, must be in the hearts of those who go to God and heaven. He who thus follows Christ, dwells in Him as his ark, refuge, and rest, and in the Father through him. This union between Christ and the souls of believers, is by the Spirit he has given them. A man may believe that God is gracious before he knows it; yet when faith has laid hold on the promises, it sets reason to work. This Spirit of God works a change; in all true Christians it changes from the power of Satan to the power of God. Consider, believer, how it changes thy heart. Dost not thou long for peace with God? Wouldst thou not forego all the world for it? No profit, pleasure, or preferment shall hinder thee from following Christ. This salvation is built upon Divine testimony, even the Spirit of God.