At any time, the commission may require persons, firms, associations, or corporations, so far as they may be subject to its jurisdiction under the terms of this act, to furnish any information which may be in his, her, its, or their possession respecting the rates, tolls, fares, charges, or practices in conducting his, hers, its, or their service. They may also be required to furnish the commission at all times for its inspection any books or papers or reports and statements. The reports and statements shall be under oath when required by the commission. The form of all reports required under this act shall be prescribed by the commission.