Amen! The Holy Spirit's Work in the Elect Children of God Eph. 1:4-5 is exactly the same for OT saints as is NT saints.
They are all given New Birth, drawn by the Father, taught by the Holy Spirit and receive His Fruit including Faith Gal. 5:22. And they receive the Blessing of Abraham Gal. 3:14 as do all God's Children of Promise Rom. 9:8.
But when the fulness of the time was come, God sent forth his Son, made of a woman, made under the law, To redeem them that were under the law, that we might receive the adoption of sons. And because ye are sons, God hath sent forth the Spirit of his Son into your hearts, crying, Abba, Father.
For as many as are led by the Spirit of God, they are the sons of God. For ye have not received the spirit of bondage again to fear; but ye have received the Spirit of adoption, whereby we cry, Abba, Father. The Spirit itself beareth witness with our spirit, that we are the children of God: And if children, then heirs; heirs of God, and joint-heirs with Christ; if so be that we suffer with him, that we may be also glorified together.