Concerning needs for credential from any visiting Persian believers

I have repeatedly written that any Persian—although he be my relative or Afnan—if he has no credential in his hand, the believers must not at all approach him, or associate with him, because all the enemies of the Cause in Persia—Yahyais, Nakazeen and Sufists—are turning their attention to America and will come in order to weaken the Cause of God. You must protect the Cause of God, and write to every one, and awaken all, that they must not meet any Persian who has not in his hand a credential in my handwriting and signature. 

- ‘Abdu’l-Baha (Portion of a Tablet to Charles Mason Remey, translated in Ramleh, Egypt, September 23, 1913; Star of the West, vol. 6. No. 12, October 15, 1915)

“firmness in the Covenant is the means of the promotion of the Word of God”

Today firmness in the Covenant is the means of the promotion of the Word of God and conducive to the effect of the word of man. Any explanation which does not accord with the Covenant will have no effect whatever. Therefore, whosoever heralds the Covenant of God, unquestionably he is confirmed. This has been tried a thousand times: Any soul who violates the Covenant and Testament in the least degree, immediately he is cut off ; even in this material world he will become afflicted with remorse and regret. 

- ‘Abdu’l-Baha (Excerpt from a Tablet to Mrs. Harriet Cline, Los Angeles, Calif.; Star of the West, vol. 6. No. 12, October 15, 1915)

Concerning any Persian believer visiting America

Convey my longing greeting to all the believers of God throughout all the cities of America and announce to them on my behalf that if any person from amongst the Persian believers who may be well known as to his character, whether man or woman—although he may be my own son or daughter— comes to America and has not a new permission for his going to America written with my own handwriting and signed with my own signature, you must not give him any attention at all. Whosoever speaks with him is a violator of the Covenant! This question is most important. Undoubtedly you must show the utmost caution. There are some wolves in sheep’s clothes who may claim to be shepherds. Whosoever from amongst the Persian believers arrives in America although he may be related to me,—that is,—even if he be my son-in-law or she be my daughter, first ask of him the letter giving him a new permission to come again to America. If he shows you any such letter, be most careful and attentive that it is my writing and my signature, that they may not be counterfeits. Then you cable to me and inquire about him. When the answer is received by you that it is correct then you meet him, otherwise do not associate with him. Announce the contents of this letter to all the believers and the maidservants of the Merciful throughout America. 

- ‘Abdu’l-Baha (Portion of a tablet to Mr. Roy C. Wilhelm, translated by Mirza Ahmad Sohrab, March 25, 1913, Paris, France. The original of this Tablet is in ‘Abdu’l- Baha’s own handwriting; Star of the West, vol. 6. No. 12, October 15, 1915)