Are we using discernment? Matt 7:6

We learned earlier about not judging, but in the very following verse Jesus talks about not judging others, and he gives examples of making good judgement like,  "don't throw your pearls to pigs", or "don't waste what is holy on people who are unholy". So this lesson is chalked full of great verses about using good discernment.  What does the bible say about discernment?