BibTeX:
@incollection{Various,
  author = {Various},
  title = {‘Abdu’l-Baha’s temporary separation from Baha’u’llah},
  booktitle = {Baha'i Stories for Children},
  url = {https://bahaistoriesforchildren.blogspot.com/2015/12/abdul-bahas-temporary-separation-from.html},
}

APA:
Various. ‘Abdu’l-Baha’s temporary separation from Baha’u’llah. In *Baha'i Stories for Children*.

MLA:
Various. "‘Abdu’l-Baha’s temporary separation from Baha’u’llah." *Baha'i Stories for Children*, n.d..

Chicago:
Various. "‘Abdu’l-Baha’s temporary separation from Baha’u’llah." In *Baha'i Stories for Children*, n.d..