I love a good proverb as it can be so colourful in the imagery it creates.
This particular one has been traced as far back as the poetry of Publius Ovidius Naso, also known as Ovid (43 BC – 17 AD), who wrote Fertilior seges est alenis semper in agris (the harvest is always more fruitful in another man’s fields).
However, the sentiment probably predates the written language.