Whoever enters the Way without a guide
will take a hundred years to travel a two-day journey.
The Prophet said "In this way you have no more
faithful companion than your works."
How can these works and this earning in the way of righteousness
be accomplished without a master, O father? Can you practice the meanest profession in the world
without a master's guidance?
Whoever undertakes a profession without a master
becomes the laughingstock of city and town.

Mathnavi translated by William Chittick pp. 122-123 as quoted in Classical Islam and Naqshbandi Sufi Tradition by Muhammad Hisham Kabbani p. 153