Jesus of Nazareth:
"Why do you notice the sliver in your friend's eye, but overlook the timber in your own? How can you say to your friend, "Let me get the sliver out of your eye," when there is that timber in your own? You phony, first take the timber out of your own eye and then you'll see well enough to remove the sliver from your own." (Matthew 7:3-5, SV)
In modern parlance: takes one to know one.
In an interview Wednesday shortly after his 21-hour talkathon to defund Obamacare had come to an end, Sen. Ted Cruz (R-TX) lamented to shock jock Rush Limbaugh that too many lawmakers think their constituents are naive.
"They think their voters are gullible rubes," Cruz said in the radio interview.