swear by
• name someone or something to show that one promises to do something or that something is the case.
• "I swear by all I hold dear that I had nothing to do with it"
• have or express great confidence in the use, value, or effectiveness of something.
• "Iris swears by her yoga"
Similar:
express confidence in,
have faith in,
put one's faith in,
trust,
have every confidence in,
believe in,
set store by,
value,
rate,
