Here is an illustration of the Spanish sayings predicar la moral en calzoncillos. While this illustration is on the book Speaking Phrases Boricua, a book about sayings used in Puerto Rico, this saying is commonly used in other Spanish speaking countries as well.
Spanish Saying: PREDICAR LA MORAL EN CALZONCILLOS
• Literal translation:
To preach morality in one’s underwear
• English equivalent:
Practice what you preach.
• Meaning:
Criticizes people that speak about morality, but do not then live their lives according to their own preaching
• Example:
“Común ver a quienes viven “Predicando la moral en calzoncillos” hablan de ética y no son éticos, HABLAN DE COSAS QUE NO PRACTICAN.” – by @IngMorrison via Twitter
Común ver a quienes viven “Predicando la moral en calzoncillos” hablan de ética y no son éticos, HABLAN DE COSAS QUE NO PRACTICAN.
— Hiddekel Morrison (@IngMorrison) November 8, 2013
Check these article for more Spanish Sayings.