O young man,
Retire from the kingdom if you wish for permanent company of the King of kings. The kingdom is a veil from the King, blessings are a veil from the Benefactor and tribulation is a veil from the One who causes tribulation. Attachment to creatures that have been given forms and shapes are shackles of the hearts, innermost beings and essences. When Allah wants to confer a lot of good on someone, He fetters him, makes him stand in His presence on the feet of his heart and provides him with a pair of wings to fly by them in the air of His Knowledge and then seek refuge in the isthmus of His nearness. Despite that, He will impose on him fear and the abandonement of any sense of conceit of his situation. He will fear that the hand of Divine jealousy will clip his wings and screen him from his knowingness after he has known what lies there. As long as the servant is in this world, he must have fear and give up any sense of vanity, regardless of the spiritual state that he attains. This is so because this world is the abode of change and substitution, while the the hereafter is the abode of permanence wherein no change or substitution takes place.
O young man,
Pass through the market of the creatures. Enter through one door and leave from another. Come away from them with your heart and intention and be like a lone bird which neither offers intimacy nor accepts it. Make sure that you do not see others and do not show yourself to them. Be like this until the appointed time comes to pass and your heart draws near the door of your Lord. You will see the hearts of the people of Allah there. They will receive you, say to you: "Congratulations on your safety" and kiss you on the forehead. The hand of subtle kindness will then come from inside the door, receive you, carry you, conduct you in a solemn procession, approach you, feed you, quench your thirst and anoint you with perfume. It will then take you out and seat you at the door, watching and waiting for any questing seeker who will come. You will take him by the hand and hand him to the hand that received you when you arrived. When this has happened to you, come out to the creatures and be among them like the physician among the sick, like a man of reason among the insane and like a compassionate father among his children. Before this happens, no respect is due to you. You would be a hypocrite with creatures, a servant for them and a follower who works for their purposes. You think you are medicating them when in fact you are associating them with Allah. Your treatment of them turns into a form of punishment for you because it is based on ignorance and inexperience. This is why the Prophet s.a.w said: 'The person who worships Allah with ignorance causes more damage than reform.'
O son, this is my hideout, the place which has witnessed my metamorphoses over the past few years bi-iznillah. Know that seclusion is requisite for those who truly wish to seek Allah. This seclusion is known as "the outward kind in which the seeker, far from people, sits alone in his cell until he comes into contact with the spiritual world. This result comes about because the external senses withdraw themselves and the inner senses extend themselves to signs from the spiritual world. The second kind of retreat (seclusion) is the hidden one, where the seeker is inwardly witnessing the secrets of the Real while he is outwardly surrounded by people. Khalwat dar anjuman is of this second type of retreat: outwardly to be with people, inwardly to be with God." - 'Principles of the Naqshbandi Path' from 'Abd ul-Khaliq Ghujduwani (d. 1220), the 11th shaykh in the Naqshbandi lineage.
O son, may Allah help you follow in our footsteps.