How to block number on iPhone 4S?

So my ex keeps messaging me and I don't want to talk to him so is there a way that I can block his messages so I don't see them? I only want to block it for a couple days so I can think straight. So is there a free app that allows me to turn it off and on? One that works please.

I know a app that is perfect for what you are asking for but, it requires your iPhone 4s to be Jailbroken in order to do it, the app is free for a few days which should give you enough time to think, its called iBlacklist.

The app is not in the app store its in cydia please tell me yours phones software verison so i can tell you if you are able to do it on not.

Settings-General-About and then version and let me know what IOS verison i have if you have 5.1.1 or below you are good.

If not there's no app in the app store that will give you the ability to do that, Threy have ones that you would need to pay for the but the quality of the app is not that good, and he will proly slip through the cracks.