The sheriff shall, besides the oaths prescribed for public officers, take an oath that the sheriff has not promised or given, nor will give, any fee, gift, gratuity, or reward for the office or for aid in procuring such office, that the sheriff will not take any fee, gift, or bribe, or gratuity for returning any person as a juror or for making any false return of any process, and that the sheriff will faithfully execute the office of sheriff to the best of such sheriff’s knowledge and ability agreeably to law.