placing ad linked posts on my site

I have a news website on technology subjects (a wp site). I was contacted by someone who said he likes to post a permanent article on my site, which will include a few links to normal places but one link to his client’s site, which is a casino and bingo site. He will hire someone to write an original article also that has related content to my site. He will pay me a reasonable amount of money for each article.

My website is an 8 year old technology news website all with original decent content, or press releases from many big firms. It has hundreds of articles inside accumulated over the years.

My question is, if I do this, does it harm my website ranking on Google? Is this a bad practice? If so, does it hurt to place a few articles anyway?