Writing on the relationship between systematic and biblical theology, John Murray writes with great balance, saying
Systematic theology is tied to exegesis. It coordinates and synthesizes the whole witness of Scripture on the various topics with which it deals. However, systematic theolgoy will fail of its task to the extent to which it discards its rootage in biblical theology as properly conceived and developed. It might seem that an undue limitation is placed upon systematic theology by requiring that the exegesis with which it is so intimately concerned should be regulated by the principle of biblical theology. And it might seem contrary to the canon so important to both exegesis and systematics, namely the analogy of Scripture. These appearances do not correspond to reality. The fact is that only when systematic theology is rooted in biblical theology does it exemplify its true function and achieve its purpose (John Murray, “Systematic Theology: Second Article,” WTJ 26, no. 1 (1963), 44-45).
(HT: Brian Payne, from his doctoral dissertation, The Summing Up of All Things in Christ and the Restoration of Human Viceregency: Implications for Ecclesiology, SBTS 2008, p. 15)