This paper focuses on Scripture-affiliated features of the Rule of Faith (regula fidei) as well as creedal structures inherent in early Rule-of-Faith formularies. It pays particular attention to traits connecting the regula fidei to Scripture, on the one hand, and to later declaratory creeds, such as the Apostles' Creed, on the other. The Rule here provides a link between Scripture and the emerging creeds. Augustine's (354-430) description of the creed as a brief summary of the regula fidei is a point of departure for the discussion. In the years around 200 CE, a concise outline summary of Christian faith was commonly referred to as "the Rule of Truth," "the Rule of Faith," or simply "the faith." It typically focused on the belief in God the Father, Jesus Christ the Son, and the Holy Spirit, together expressing the divine Name (cf. Matt 28:19), alongside a formulation of the Christological kerygma. Candidates preparing for baptism were familiarised with this triadic (or binitarian) Rule-of-Faith summary, side by side with their instruction in the Sacred Scriptures. By integrating this ancient form of Triune teaching with a Christological formulary, the influential second-century bishop Irenaeus of Lyons (ca. 125-202) could phrase such a summary statement under three articles of faith (about God the Father, the Son Jesus Christ, and the Holy Spirit), with the main portion of the Christological material included under the third article about the Holy Spirit - the Spirit of prophecy (Iren. Haer. I, 10.1). That the Christological portion of the creedal formulation for Irenaeus is here an integrated part of the third article of faith indicates that the third article about the Spirit is directly linked to scriptural prophecy and Christological fulfillment. In other ways, too, the Rule of Faith is closely linked to Scripture and the scriptural account and may be presented either in longer form or as a brief summary of the faith.