Make haste slowly.
As quoted in Houghton, Mifflin, Familiar Short Sayings of Great Men (1882), p. 25
Variant translations: "Hurry slowly"; or, "Hasten slowly." Originally quoted in Greek, in Suetonius, II. Augustus, section 25, but better known in the Latin form, as reported in Chambers Dictionary of Quotations (1997), p. 50