Now it is only a pure philosophy that we can look for the moral law in its purity and
(and, in a practical matter, this is of the utmost consequence): we must, therefore, begin with pure philosophy (metaphysic), and without it there cannot be any moral philosophy at all.
The-Critique-of-Practical-Reason-The-Metaphysical-Elements-of-Ethics-and-Fundamental-Principles-of-the-Metaphysic-of-Morals-by-Immanuel-Kant
