The Pharisees were a group of powerful priests that believed
that they were holier than the common Jew. Elitists in other words.
They followed all the ten commandents many other rules made up by
themselves to prove their so-called holiness. They were in reality
more form than substance. i.e they don't help their neighbour
because the ten commandents doesn't say so word for
word. Unless it benefited them of course.
When Jesus came along and started helping people left and right,
not discriminating against the poor, the pariah, and other social
outcasts, this showed up the Pharisees for the hypocrites they
really were.
For the benefit of those that don't understand the ten commandants
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First five commandants - love God
Second five commandants - love man