Before hearing any testimony, arbitrators selected as prescribed in this chapter must be sworn, by an officer authorized by law to administer an oath, faithfully and fairly to hear and examine the matters in controversy and to make a just award according to the best of their understanding, unless the oath is waived by the written consent of the parties to the submission or contract or their attorneys, or the parties have continued with the arbitration without objection to the failure of the arbitrators to take the oath.