Where is it Sunnah to tie the hands in Salah?

Hazrat Waa'il bin Hujr (Radiyallahu Anhu) said: "I saw Rasulullah (Sallallaahu Alaihi Wasallam) placing his right hand on his left hand below the navel in Salah." (Ibn Abu Shaibah) - [This Hadith is Saheeh (Authentic)].

[English version of "A cote li sounnnte attache la main dans namaz ?" – Al Jamiat – Vol.1 No.13]