swear

utter obscenities or profanities; "The drunken men were cursing loudly in the street"

to declare or affirm solemnly and formally as true; "Before God I swear I am innocent"

promise solemnly; take an oath

make a deposition; declare under oath

have confidence or faith in; "We can trust in God"; "Rely on your friends"; "bank on your good education"; "I swear by my grandmother's recipes"