Located places of pilgrimage, it was a custom to tear off a piece of one's clothing and tie it in a knot on a nearby shrub or tree. Other pieces of cloth can be used also.
The branches of a wild fig-tree near by were covered with rags of different colours, which we learned on inquiry betokened the visits of those people who resort hither to seek the divine intervention in their behalf. Such as are about to undertake a journey, barren women, and the sick and infirm, are the principal visitors on ordinary occasions, and these record their vows, by tearing off a shred from their garments, and tying it to the tree before mentioned. The same custom prevails extensively among the Mohammedans throughout Turkey, and it is not uncommon for the traveller to meet with shrubs and bushes on the road literally hid under these votive offerings. Badger 1852, p 99; of a trip to Mar Danial Mountain
Badger, George Percy. 1852. The Nestorians and their Rituals. https://books.google.iq/books?id=Oo8AAAAAcAAJ