Why is the senate on oath or affirmation when trying impeachment?

The Senate takes an oath or affirmation during impeachment trials to ensure that senators uphold their duties with integrity and impartiality. This solemn commitment emphasizes the seriousness of the proceedings, as impeachment is a constitutional process that can remove a sitting president or other officials from office. The oath reinforces the senators' obligation to act fairly and based on the evidence presented, maintaining the integrity of the judicial process within the legislative branch.