Before an attorney may practice in any court in the Commonwealth, he shall take the oath of fidelity to the Commonwealth, stating that he will honestly demean himself in the practice of law and execute his office of attorney-at-law to the best of his ability. An attorney who has qualified before the Supreme Court of Virginia shall be qualified to practice in all courts of the Commonwealth. An attorney who has qualified before a court other than the Supreme Court shall be qualified to practice only in the court which administered his oath. Each court in which an attorney intends to practice may require the attorney to produce satisfactory evidence of his licensure or authorization.