Read how old John Gill described the work of the Spirit in this verse….
God hath sent forth the Spirit of his Son into your hearts, crying Abba, Father.
The Syriac and Arabic versions read, “our Father”; all the three divine persons here appear, as having a concern in this business, as before observed; here are God and his Son, and the Spirit of his Son, said to be sent; by whom is designed not any work of his upon the heart, nor any of his gifts and graces; but he himself in person, even the same Spirit of God that moved upon the face of the waters at the creation of the world, and moved holy men of God to write the Scriptures; who formed and filled the human nature of Christ, and descended on him as a dove; and by whom Christ and his apostles wrought their miracles; and who is called the Spirit of his Son; as he is frequently by the Jews (g), רוחו של מלך משיח, “the Spirit of the King Messiah”; and sometimes (h) רוח מימריה, “the Spirit of his word”, the essential word of God; because he proceeds from him as from the Father, and because he dwells in him, in an eminent manner, as Mediator, and is sent by virtue of his mediation and intercession; and he is the rather mentioned under this character, because adoption proceeds upon the natural sonship of Christ, and is what is the peculiar office of the Spirit to testify. When he is said to be “sent”, it does not suppose any local motion or change of place in him, who is a spirit infinite, immense, and omnipresent;
nor any inferiority to the Father that sends him, or to the Son whose Spirit he is; for he is one God with the Father and Son, and with the Father is the sender of Christ, Isa 48:16,
but it regards his peculiar office in this affair of adoption, by agreement of all the three persons; the Father predestinated to it, the Son redeems, that it might be received, and the Spirit is sent to discover, apply, and bear witness to it; which is a wondrous instance of the grace of God.
The place where he is sent is “into” the “heart”: where he is as a principle of spiritual life, and which he furnishes and supplies with all grace; where he dwells as in his temple, and is the evidence of God’s dwelling there, and also of interest in Christ; is there as a pledge and an earnest of future glory; and the whole is a surprising instance of condescending grace.
The work he does there is various, and consists of divers parts; as convincing of sin, and righteousness, working faith, and acting the part of a comforter; but what is here referred to, is the discharge of his office as a spirit of adoption, “crying Abba, Father”.
The word Abba is an Hebrew, or rather a Syriac or Chaldee word, signifying “father”; and which is added for explanation sake; and its repetition may denote the vehemency of filial affection, the strength of faith and confidence as to interest in the relation; and being expressed both in Hebrew and Greek, may show that God is the Father both of Jews and Gentiles, and that there is but one Father of all; and if it might not be thought too curious an observation, it may be remarked that the word “Abba”, read backwards or forwards, is the same pronunciation, and may teach us that God is the Father of his people in adversity as well as in prosperity. The act of “crying”, though it is here ascribed to the Spirit, yet is not properly his, but the believers; and is attributed to him because he excites, encourages, and assists them as a spirit of adoption to call God their Father; and may be understood both of the secret internal crying of the soul, or exercise of faith on God as its Father, and of an open outward invocation of him as such, with much confidence, freedom, and boldness.