Socrates's expression for "Sound body makes for a sound mind"; in the
original Greek, please.

The maxim to which you refer is almost always quoted in Latin, and
attributed to Juvenal:

"Juvenal mocks the foolishness of most prayers and wishes addressed to
the Gods and exhorts his readers that the only thing one should pray
for is a sound mind in (or and) a healthy body. Orandum est ut sit
mens sana in corpore sano. He never implied that a sound mind can only
be found in a healthy body."

http://www.nybooks.com/articles/18123

i m Greek .You mean to write it in Greek language or spell it as in
Greek? its "nous igiis en somati igii"