The Holy Spirit not mentioned in the Old Testament

In the Word of the Old Testament the Holy Spirit is nowhere mentioned, but the Spirit of holiness,—and only in three places; once in David (Ps. li. 13), and twice in Isaiah (lxiii. 10, 11). But in the Word of the New Testament it is frequently men­tioned,—in the Evangelists, as well as in the Acts of the Apostles, and in their Epistles. The reason is, that then—when the Lord came into the world,—there first was the Holy Spirit; fox it goes forth out of Him from the Father. (TCR n. 158)