Related Clues:

• Corroborate
• Show it's so
• Establish the authenticity of
• Leave no doubt
• Affirm, with 'to'
• Certify (to)
• Bear witness (to)
• Warrant, with 'to'
• Show to be so
• Give evidence - sounds a trial
• Certify or bear witness
• Give evidence, bear witness
• Ascertain truth or accuracy
• Ratify or verify
• Assert, state as fact