One source said:
Easier said than done
1. Meaning: Sometimes it's easy to say what should be done, but harder to do.
2. Origin: Not found
EASIER SAID THAN DONE is an interesting American idiom.
Dating back to the 1500's, this proverb implies that it is easier to advise someone on how to complete a task than it is to actually do the work yourself. You might hear an American say, "It only took you five minutes to explain to me how to repair my leaky faucet, but it took me two hours to actually do the work. Fixing that faucet was easier said than done." Telling someone else how to do something is always easier than following your own directions! It's EASIER SAID THAN DONE.
http://www.knls.org/English/trascripts/idiom001.htm
http://www.xrefer.com/entry/631184
http://www.cybered.co.th/eng/proverb.htm
I suppose it could be a Latin proverb:
Lettere sagt enn gjort.
(Easier said than done.)
~Latin