Galatians 4:6

Lest the Jews should claim the adoption as peculiar to them, the apostle tells them that these Gentiles were also sons; and in confirmation of that, he saith, that God had sent the Spirit of his Son into their hearts: not that the Holy Spirit is not the Spirit of the Father, as well as of Christ; but he calleth him the Spirit of Christ, because he had made adoption the end and fruit of redemption; and redemption is every where made the work of the Son. The apostle saith, Romans 9:4, that the adoption belongeth to the Israelites: the Jews were the first people whom God dignified with the name of his sons, his first-born, Exodus 4:22; and so many of them as believed also received the Spirit, Ezekiel 36:27; but the full effusion of the Spirit was reserved to gospel times, and until the time that Christ ascended, 1 Thessalonians 7:39, 1 Thessalonians 16:7. After which the Spirit was poured out in the days of Pentecost, Acts 2:1, whose effects were evident, not only in power to work miracles, and speak with divers tongues, (which were not common to all believers), but also in a variety of spiritual gifts and habits, amongst which this was one, teaching them to cry, Abba, Father. Crying, (it is expounded, Romans 8:15, whereby we cry, that is, through whose influence and working in us we cry), Abba, Father, that is, Father, Father: which not only signifieth the Spirit's influence upon believers words in prayer, first conceived in the heart, then uttered by the lips; but chiefly those habits of grace, by which we pray acceptably; faith and holy boldness, by which we call God Father; zeal and fervency, by which we are importunate with God, and say, Father, Father. Which were now not the privileges of Jews only, but of these Galatians also, who were by nature Gentiles, and strangers to God; and a certain evidence of their concern in the redemption of Christ, and that they also might expect salvation from him.