BibTeX:
@incollection{Various,
  author = {Various},
  title = {Three Hearts United into One},
  booktitle = {bahaistories.com archive},
  url = {https://bahaistories.com/subject/inner-life},
}

APA:
Various. Three Hearts United into One. In *bahaistories.com archive*.

MLA:
Various. "Three Hearts United into One." *bahaistories.com archive*, n.d..

Chicago:
Various. "Three Hearts United into One." In *bahaistories.com archive*, n.d..