Once the Baal Shem stopped on the threshold of a House of Prayer and refused to go in. “I cannot go in,” he said. “It is crowded with teachings and prayers from wall to wall and floor to ceiling. How could there be room for me?”
And when he saw that those around him were staring at him and did not know what he meant, he added: “The words from the lips of those whose teaching and praying does not come from the hearts lifted to heaven, cannot rise, but fill the house from wall to wall and floor to ceiling.”
Masha'Allah! Also can recall the words of the Sufi Bayazid Bistami who said: "The thickest veils between man and Allah are the wise man’s wisdom, the worshiper’s worship and the devotion of the devout."