We have previously written and sent out a detailed letter regarding the education of children...
Translated
oceanoflights.org/abdul-baha-tablets-talks-bahai-library-054-en/
[Extract from a Tablet of 'Abdu'l‑Bahá]
We have previously written and sent out a detailed letter regarding the education of children in faith, certitude, learning, and spiritual knowledge, and their being taught to call upon the Heavenly Kingdom with suppliant hearts.
It is certain that ye will exert every effort toward this end.
---'Abdu'l‑Bahá