The Aramaic noun behilu means haste or hurry — the state of urgent, rapid action. It is used in the biblical Aramaic portions of Ezra, describing the manner in which royal commands were to be executed: swiftly, without delay.
In Ezra 6:13, the Persian officials carry out the decree of Darius 'with all diligence (behilu)' — swiftly and completely. The word captures the urgency that characterizes the execution of sovereign decrees. Theologically, the rapid compliance of Persian officials with a decree protecting the rebuilding of God's temple illustrates the overarching sovereignty of God who bends the hearts of kings to accomplish His redemptive purposes. Even foreign rulers serve, knowingly or not, the agenda of the King of kings.