Collocations for oath - noun

sacred, solemn
blood
Hippocratic
a doctor's Hippocratic oath

presidential
loyalty (esp. AmE)

swear, take
He took an oath of allegiance to his adopted country.

sign
break, violate
keep, uphold

oath of
an oath of allegiance
an oath of loyalty

administer
Only a judge is allowed to administer the oath.

on oath (esp. BrE), under oath
He swore on oath that he had never seen me before.
Witnesses must testify under oath.