BibTeX:
@incollection{Various,
  author = {Various},
  title = {Bahá'u'lláh's First Imprisonment},
  booktitle = {Baha'i Stories Blog},
  url = {https://bahaistories.blogspot.com/2017/04/circa-1848-bahaullahs-first-imprisonment.html},
}

APA:
Various. Bahá'u'lláh's First Imprisonment. In *Baha'i Stories Blog*.

MLA:
Various. "Bahá'u'lláh's First Imprisonment." *Baha'i Stories Blog*, n.d..

Chicago:
Various. "Bahá'u'lláh's First Imprisonment." In *Baha'i Stories Blog*, n.d..