Parable of the Sower
This is a parable about a sower (I'm pretty sure there is another one ~ but I have been known to be wrong before ). Rather than trying to summarise here's a quote of it:
"A farmer went out to plant some seed. 4As he scattered it across his field, some seeds fell on a footpath, and the birds came and ate them. 5Other seeds fell on shallow soil with underlying rock. The plants sprang up quickly, 6but they soon wilted beneath the hot sun and died because the roots had no nourishment in the shallow soil. 7Other seeds fell among thorns that shot up and choked out the tender blades. 8But some seeds fell on fertile soil and produced a crop that was thirty, sixty, and even a hundred times as much as had been planted."
Jesus teaches this to a crowd, but it is only later that he explains it to the disciples. To be honest I'm not 100% sure about why this was necessary other than to fulfill Isaiah's prophecy. Seeing as God could have had the prophecy say something different in the first place that's really not a good reason. Although it does have to be said that Jesus did give it to the Jewish leaders pretty straight at times, and didn't mince his words so if you think you know please add a comment for all to see.