Some Ans. Questions 2014 by -'Abdu'l-Bahá- 1 Para

To summarize, not a single soul, whether friend or foe, who attained Baha'u'llah's presence failed to acknowledge and attest to His greatness. Although he might not become a believer, he would invariably bear witness to His greatness. No sooner would someone appear before Him than the encounter would produce such an impression as to prevent him, in most cases, from uttering a word. How often would a bitter enemy resolve in his heart to say such-and-such or to argue so-and-so when he had attained His presence, only to find himself amazed, bewildered, and reduced to utter silence! (9:20)

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