Mencius - Book 4, Part 1, Chapter 19A

Mencius said, 'Of services, which is the greatest? The service of parents is the greatest. Of charges, which is the greatest ? The charge of one's self is the greatest. That those who do not fail to keep themselves are able to serve their parents is what I have heard. But I have never heard of any, who, having failed to keep themselves, were able notwithstanding to serve their parents.

'There are many services, but the service of parents is the root of all others. There are many charges, but the charge of one's self is the root of all others.
~ James Legge translation via nothingistic.org ~

Go here to read the introductory post to this serialized version of the Works of Mencius.