Confusion in disallow syntax

[jsusan2410]

I have a confusion with disallow syntax here.

I want to disallow a sub folder and its children pages. I asked my friend and he gave me this format.
Disallow: /xyz/en/ru/

he suggested the user agent will block this page and complete folder in this format.

however I found another format in some other blogs:
Disallow: /xyz/en/ru/*  which convinces me that it will block complete folder and its children pages.

Please suggest me which format is right or preferred.