“Don’t give that which is Holy to the dogs, neither throw your pearls before the pigs, lest perhaps they trample them under their feet, and turn and tear you to pieces” Matthew 7:6
This is from Jesus’s sermon on the Mount. It warns against sharing valuable, sacred, or deeply meaningful knowledge with those who cannot appreciate or understand it. As such efforts are futile, and the recipient may disregard, ridicule, or react with hostility, trampling the message and tearing the giver.
Jesus advises us against wasting spiritual truths (pearls) on inreceptive, antagonistic, or disrespectful people (swine).
Pearls represent wisdom, valuable spiritual truths, or the gospel. And swine represent individuals who are not only incapable of appreciating the value but are also destructive to it.
It is a call for discernment, advising that while sharing truth is important, it should not be forced upon those who are actively hostile to it. It is closely related to the idea of not being a judgmental hypocrite.
The modern application of this can be described as not wasting time, effort, or resources such as advice, love, and trust on people who do not value them.
From Pity to Praise 