The descendants of Azal, with their mother's milk, drank hatred of Bahá'u'lláh

The friends are sometimes surprisingly naive and superficial in their approach to the subject of Covenant-breakers. They do not seem to understand that the descendants of Azal, with their mother's milk, drank hatred of Bahá'u'lláh, just as the descendants of Muhammad-Ali and his relatives have imbibed from babyhood a false concept of the Master. It takes practically a miracle to overcome this lifelong habit of wrong thought. Now, however, he has told the German believers to shun her.

(From a letter dated 18 August 1949 written on behalf of the Guardian to a National Spiritual Assembly)

https://bahai-library.com/pdf/compilations/nonassociation_covenant_breakers.pdf