KHUTBA
The word khutba (pl. khutub) means public address, speech, lecture, discourse, oration or sermon. In past, the khatib (preacher) traditionally invoked the name of the recognized caliph after the Friday prayer at a congregational mosque (jam'ah masjid), and during pilgrimage and at the time of special festivities.
Source
Encyclopaedia of Ismailism by Mumtaz Ali Tajddin