for somebody's sake= in order to help or bring advantage to someone: Please do it, for David's sake. Their parents only stayed together for the sake of the children. I hope for both our sakes that you're right! source: http://dictionary.cambridge.org/dictionary/english/sake

"sake" is a rich word. There are many examples of its use in sentences here: http://sentence.yourdictionary.com/sake for the sake of something/someone = for the deepest interests of someone/something. e.g. I am changing job for the sake of my family. My current job doesn't allow me to spend enough time with my children. Are you interested in trying to make your own sentences with "sake"?