What is the origin of the idiom "cast pearls before swine" and when to use it?

The origin of the idiom "cast pearls before swine" is biblical, and it is derived from a passage in the New Testament where Jesus warns his followers not to waste their teachings on people who are not receptive to them. The phrase has been in use in English since at least the early 17th century, and it is often applied to situations where someone is making a great effort to share something valuable, such as knowledge or wisdom, with someone who is not interested or capable of understanding it. In general, the phrase is used to caution people against investing their time and energy in situations where their efforts are unlikely to be appreciated or reciprocated.