Are the messages requesting dhikr or the remembrance of Allah (such as "Subhan Allah") that a person sends considered ongoing charity (sadaqah jariyah) for them after their death, and does the reward continue every time the recipient reads them?

When a person dies, his deeds cease except for three: an ongoing charity (sadaqah jariyah), knowledge from which others benefit, or a righteous child who supplicates for him. Ongoing charity is an endowment (waqf) and similar deeds whose benefit endures. Messages that remind of good and enjoin what is right may be considered knowledge from which others benefit, and the reward for benefiting from them accrues to the deceased, for "the one who points to good is like the one who does it," and "whoever calls to guidance will have a reward similar to that of those who follow him."