On a fountain in Preveli monastery in South West Crete is a fountain with this inscription
Which written out is
νίψον ἀνομήματα μὴ μόναν ὄψιν
Wash your sins not just your face
When I saw it, I didn’t twig that it was a palindrome. A little research shows that it is attributed to St Gregory of Nazianzus and is to be found at various places round the world including Hagia Sophia in Istanbul and various French and English churches.