Cord between hands on prayer

[Delfifini]

Hello everyone!

I have aquestion about cords or strings in praying o meditation. I've seen images of monks holding a white cord between their hands while praying. I wanted to know if there is a meaning for this.
I am making an Asalha Puja Day salutation and I found this kind of image, but don't really know if it applies for this kind of celebration.

Thanks!

[Fortyeightvows]

They are likely monks of the southern tradition, that is Theravada Buddhism. I've been told it is goes back to the white strings that Brahman preists of India would wear.
It seems to be a form of both correspondence and contagion magic.