The expression “May you live forever”
Question

                Is it permissible to say to someone, “May you live forever”?.
Praise be to Allah.Shaykh Muhammad ibn ‘Uthaymeen (may Allaah 
    have mercy on him) said: “Saying ‘May you live forever’ is a kind of transgression in du’aa’, because living forever is impossible and is contrary 
    to what Allaah says. Allaah says (interpretation of the meaning): 
“Whatsoever is on it (the earth) will 
    perish.
 And the Face of your Lord full of Majesty and Honour will remain forever”
[al-Rahmaan 55:26] 
“And We granted not to any human being 
    immortality before you (O Muhammad); then if you die, would they live forever?”
[al-Anbiya’ 21:34]
From Majmoo’ Fataawa Ibn ‘Uthaymeen (may Allaah have 
    mercy on him), 3/69.