Complex sentence: Gautama Buddha is said to have said that the four sites most worthy of pilgrimage for his followers to visit, and producing a feeling of spiritual urgency, are: The Buddha mentions these four pilgrimage sites in the Mahaparinibbana Sutta.
Split into simpler sentences: Gautama Buddha is said to have identified four sites most worthy of pilgrimage for his followers, saying that they would produce a feeling of spiritual urgency. These are: The Buddha mentions these four pilgrimage sites in the Mahaparinibbana Sutta.