This short letter is one of thirty-seven still extant writings addressed by Nichiren Daishonin to his faithful disciple Shijō Kingo. Kingo was under great pressure from his lord, Ema, and other fellow warriors to renounce his support for the Daishonin. This letter was written to encourage Kingo and to strengthen his resolve.

https://www.nichirenlibrary.org/en/wnd-1/Content/56