BibTeX:
@incollection{AbdulBah1886,
  author = {'Abdu'l-Bahá},
  title = {Untaught Wisdom and the Call of the Báb},
  booktitle = {A Traveler's Narrative Written to Illustrate the Episode of the Báb},
  year = {1886},
  publisher = {Bahá'í Publishing Trust},
}

APA:
'Abdu'l-Bahá. (1886). Untaught Wisdom and the Call of the Báb. In *A Traveler's Narrative Written to Illustrate the Episode of the Báb*. Bahá'í Publishing Trust.

MLA:
'Abdu'l-Bahá. "Untaught Wisdom and the Call of the Báb." *A Traveler's Narrative Written to Illustrate the Episode of the Báb*, Bahá'í Publishing Trust, 1886.

Chicago:
'Abdu'l-Bahá. "Untaught Wisdom and the Call of the Báb." In *A Traveler's Narrative Written to Illustrate the Episode of the Báb*, Bahá'í Publishing Trust, 1886.