I personally would advise against telling work he is looking for other jobs, I've seen bad things happen because of that, or it doesn't make a difference. It's better to play your hand close to your chest and to be like a monkey - don't let go of one branch until you've firmly got your hand on the next (aka signed contract and start date). Conversely, once he has an offer of employment from somewhere else then HE has the power, he can choose to take that offer or use it to negotiate higher pay/other conditions for the current business to keep him. Until you've got that offer though, any threat of leaving is just hot air. They'll either just ignore the threats or will just say "fine, leave" knowing that unless he is in a very good financial position that he can just stop working while he looks for a new job, that he can't afford to leave until that new job materialised, and then they'll act if they want to keep him. In the mean time they'll continue to treat him like crap, or they might treat him worse because he's offended them but letting them know his intensions of leaving.