BibTeX:
@incollection{NabliAamtranslatedandeditedbyShoghiEffendi,
  author = {Nabíl-i-A'ẓam (translated and edited by Shoghi Effendi)},
  title = {No Word but the Truth},
  booktitle = {The Dawn-Breakers: Nabíl's Narrative of the Early Days of the Bahá'í Revelation},
}

APA:
Nabíl-i-A'ẓam (translated and edited by Shoghi Effendi). No Word but the Truth. In *The Dawn-Breakers: Nabíl's Narrative of the Early Days of the Bahá'í Revelation*.

MLA:
Nabíl-i-A'ẓam (translated and edited by Shoghi Effendi). "No Word but the Truth." *The Dawn-Breakers: Nabíl's Narrative of the Early Days of the Bahá'í Revelation*, n.d..

Chicago:
Nabíl-i-A'ẓam (translated and edited by Shoghi Effendi). "No Word but the Truth." In *The Dawn-Breakers: Nabíl's Narrative of the Early Days of the Bahá'í Revelation*, n.d..