TAYUMMUM
Hadrat Jabir (Radi Allaahu Ta’ala Anhu) narrated that the Messenger of ALLAH (Sallallahu Alaihi Wa Sallam) said: “The chief thing in tayammum is to strike the hand on (clean) ground, once for the face and and again for both the hands upto the elbows. [Mustadrak]
The Prophet (Sallallahu Alaihi Wa Sallam) would not perform tayammum afresh for each Salaah. He did not even enjoin this either; he has made it a complete substitute for ablution. [Zadul Ma’ad]