I have heard about you and about your cures, which are done by you without drugs; for example you make the blind see again; you make the lame walk; you cleanse lepers; you drive out unclean spirits; you heal those who have been tormented by disease over long periods. Having heard all this of you I had one of two ideas: either that you are Son of God, who do these things, or that you are God. So then I write to you and ask you to and to come to me to cure the suffering I have, and then to be with me; for I have also heard that the Jews murmur against you and wish to do you ill. My city is very small but distinguished and adequate for both of us to live here in peace. (http://anastasis.org.uk/16august.htm)]
Ananias arrived in Jerusalem and saw the Lord surrounded by people. He was not able to get close to Him because of the large throng of people listening to the preaching of the Savior. Then he stood on a high rock and attempted to paint the portrait of the Lord Jesus Christ from afar, but this effort was not successful. The Savior saw him, called to him by name and gave him a short letter for Abgar in which He praised the faith of this ruler. He also promised to send His disciple to heal him of his leprosy and guide him to salvation.
[Blessed are you, Agbar, who have believed in me, though you have not seen me. For it is written of me that those who have seen me do not believe in me so that those who have not seen me may believe and live. As to what you wrote about my coming to you, it is necessary that I accomplish all that I was sent out to do and, after I have accomplished it, to be taken up to the Father who sent me. And when I have been taken up I will send you one of my Disciples, named Thaddaios, he will heal your disease and grant you and those with you eternal life and peace, and he will make your city such that no enemy can prevail against it.
[The Persians had built a huge fire outside the city wall; when the Bishop approached with the Holy Napkin, a violent wind fell upon the fire, turning it back upon the Persians, who fled in defeat. (http://goarch.org/chapel/saints_view?contentid=167)]
Orthodox tradition has long seen the Mandylion (the cloth that Christ imprinted His image on in life) as distict from the burial cloths of Christ. A few modern researchers (heterodox and some Orthodox) however have proposed that the Mandylion of Orthodox tradition is in fact the burial shroud of Christ (i.e. the Shroud of Turin) upon which His image was imprinted.
(Of course it is very important to remain cautious about such theories. Also, this isn't the juncture to fully discuss the authenticity of the Shroud of Turin. Right now it's my impression that the evidence is mixed, while some Orthodox do see it as authentic. See the link below the quote for a full article about it, or pictures here from an Orthodox service before the Shroud this past year: http://www.mospat.ru/en/2010/05/18/news18357/)
The following is an excerpt from an article by an Orthodox source on the Shroud of Turin:
"A 6th century text refers to the Mandylion as a "tetradiplon'--"doubled in four." A most curious choice of word, according to Cambridge University's Professor Lampe, editor of the 'Lexicon of Patristic Greek'; in all literature it occurs only in association with the image of Edessa, being scarcely, therefore, an idle turn of phrase."  As Wilson convincingly suggests, if the Shroud of Turin were folded in this manner, i.e., doubled four times, the viewer would see nothing but the head. And if this folded cloth were attached to a board (as the Mandylion is said to have been), those who venerated the holy image could well have been ignorant of the fact that they were looking at but a portion of what was actually a full-length image, particularly if this image had been sealed up for so many years.
This theory is strengthened by the distinct crease marks photographically discerned on the Shroud in the very locations suggested by the "doubled in four." And although the evidence of pollen is by no means conclusive (it can be blown hundreds of miles), Dr. Frei identified on the Shroud pollen not only from the Constantinople and Jerusalem areas, but also from the Anatolian steppes where Edessa is located...
But none of this, as fascinating as it is, has been conclusively proven. We can only say that the historical evidence thus far uncovered, and the scientific evidence of the Shroud of Turin itself, does indeed suggest this explanation, But the point is that if the Shroud is also the Mandylion, not only does it have an Orthodox history, but it also explains why it seems to have no separate feast or service."
We can benefit spiritually from both the Shroud and the Mandylion, regardless of whether not they are one and the same. They are both tangible signs that Christ our God, the eternal Word of the Father, really took on flesh for our salvation. By approaching them (or any icons of Christ for that matter) and showing them veneration, we show Christ love and worship, and we can receive grace and healing from Him as did the woman with an issue of blood, who was healed by grasping the fringe of Christ's garment. (Luke 8:43-48) Gazing on Christ's sacred image, we can remember His words from the Gospel of Luke (used on the feast of the Holy Mandylion): "Blessed are the eyes which see what you see! For I tell you that many prophets and kings desired to see what you see, and did not see it, and to hear what you hear, and did not hear it." (Luke 10:23-24)
I honour the imprint of your face, O Saviour.
Alive you wiped your face upon a cloth,
A final burial cloth you wore when dead.
Maker of all, my Christ, a tile once made
By hand now bears your form not made by hand.