Matthew 15:14

Leave them alone. They are blind guides of the blind; and if a blind man leads a blind man, both will fall into some pit."

Luke 6:39

He also spoke to them in figurative language. "Can a blind man lead a blind man?" He asked; "would not both fall into the ditch?

Matthew 23:16-24

"Alas for you, you blind guides, who say, "'Whoever swears by the Sanctuary it is nothing; but whoever swears by the gold of the Sanctuary, is bound by the oath.'

1 Timothy 6:5

and persistent wranglings on the part of people whose intellects are disordered and they themselves blinded to all knowledge of the truth; who imagine that godliness means gain.

2 Peter 2:1

But there were also false prophets among the people, as there will be teachers of falsehood among you also, who will cunningly introduce fatal divisions, disowning even the Sovereign Lord who has redeemed them, and bringing on themselves swift destruction.

2 Peter 2:17

These people are wells without water, mists driven along by a storm, men for whom the dense darkness has been reserved.

Revelation 19:20

who had done the miracles in his presence with which he had led astray those who had received the mark of the Wild Beast, and those who worshipped his statue. Both of them were thrown alive into the Lake of fire that was all ablaze with sulphur.

Revelation 22:15

The unclean are shut out, and so are all who practise magic, all fornicators, all murderers, and those who worship idols, and every one who loves falsehood and tells lies.

Treasury of Scripture Knowledge

Summary

Let them alone: they be blind leaders of the blind. And if the blind lead the blind, both shall fall into the ditch.

Bible References

Let

1 Timothy 6:5
and persistent wranglings on the part of people whose intellects are disordered and they themselves blinded to all knowledge of the truth; who imagine that godliness means gain.

They

Matthew 23:16
"Alas for you, you blind guides, who say, "'Whoever swears by the Sanctuary it is nothing; but whoever swears by the gold of the Sanctuary, is bound by the oath.'
Luke 6:39
He also spoke to them in figurative language. "Can a blind man lead a blind man?" He asked; "would not both fall into the ditch?

And if

2 Peter 2:1
But there were also false prophets among the people, as there will be teachers of falsehood among you also, who will cunningly introduce fatal divisions, disowning even the Sovereign Lord who has redeemed them, and bringing on themselves swift destruction.
Revelation 19:20
who had done the miracles in his presence with which he had led astray those who had received the mark of the Wild Beast, and those who worshipped his statue. Both of them were thrown alive into the Lake of fire that was all ablaze with sulphur.
Revelation 22:15
The unclean are shut out, and so are all who practise magic, all fornicators, all murderers, and those who worship idols, and every one who loves falsehood and tells lies.

General references

Mark 8:13
So He left them, went on board again, and came away to the other side.
Luke 12:57
"Why, too, do you not of yourselves arrive at just conclusions?
Luke 20:8
"Nor will I tell you," said Jesus, "by what authority I do these things."
1 Corinthians 14:38
But if any one is ignorant, let him be ignorant.