Article 44 of Law of Evidence

Each witness shall give his testimony separately, without the presence of the other witnesses whose testimony has not been heard. Witnesses in rebuttal shall be heard at the same hearing at which witnesses in support were heard, unless an impediment prevents this. If the evidentiary hearing is adjourned to another hearing, pronouncement of the adjournment shall constitute a summons to the witnesses present to attend that hearing, unless the court expressly exempts them from attendance. The witness shall take the oath by saying: I swear by Almighty God.