Tablets of Visitation refers to specific prayers used in the Bahá'í Faith while visiting the shrines of its founders or martyrs.
The Báb, Bahá'u'lláh and `Abdu'l-Bahá wrote many Tablets of Visitation. The Tablet of Visitation for the Báb and Bahá'u'lláh is a prayer that is used during visits to the Shrine of Bahá'u'lláh and of the Báb, and is also used during Bahá'í holy days associated with them; the tablet is composed of passages taken from several of Bahá'u'lláh's writings. There is also a Tablet of Visitation for `Abdu'l-Bahá which is a prayer that expresses humility and selflessness.
References
Tablet of Visitation Wikipedia(Text) CC BY-SA