"Be grateful for whoever comes, because each guest has been sent as a guide from beyond" –Rumi
Khidr as the one who travels over land and sea, mountains and valleys searching and longing to meet the friends of God. Hakim at-Tirmidhi tells about Khidr a remarkable tale. Khidr knew from the beginning of time what would happen to these friends of God. He wished to see in his own life what would become of their works. Khidr received such a long life that he experienced all of it up to the Day of Resurrection.
Rumi has told the following tale: A certain shahna (a chief of police) was active as such in the days of Harun ar-Rashid. Khidr visited him every day. This shahna suddenly retired from his job. Khidr then stopped visiting him. The poor shahna started to worry as Khidr seemed to ignore him.
One night it was made clear to him his value was connected to his being active in his work. The next morning he went to the caliph and asked for his job back. Harun ar-Rashid asked him what had taken place and he explained it all. Khidr immediately thereafter again started to visit the reinstated shahna. People forget a person's 'presence' is not always visible.
The shahna then wanted to know of Khidr why he had stopped visiting him. Khidr then said: "The value of your position is that you sit in the Diwaan and protect the poor and the needy and free them from the claws of their oppressors. You should know that this is better than thousand Sufi retreats!"
This Sufi tale is found: http://www.chishti.ru/sufi_khidr.htm