The phrase "unending source" means something that keeps providing or producing without ever running out or stopping.
Sentences with «unending source»
If it weren't for the wonderful casts they always manage to wrangle together and a seemingly unending source of immaturity on my part these movies would be absolute garbage. (nerdlocker.com)
If religion were not such an unending source of trouble in the world, it would just be funny and pitiful. (religion.blogs.cnn.com)
Those moments in turn became the backbone of a new kind of media landscape in which websites like the one you're reading understood that the culture of basketball was an unending source of content generation. (sbnation.com)