The gardener's dog doesn't eat cabbages and will let no one else eat them.
(French: Le chien du jardinier ne mange point de choux, et n'en laisse pas manger aux autres.)
The source for the proverb is A Polyglot of Foreign Proverbs by Henry G. Bohn (GoogleBooks). The poster is made with AutoMotivator. The image is by Todd Dwyer at Flickr.