How do I hide names from incoming messages on whatsapp on my iphone5
Basically, when it comes to WhatsApp there are two sets of Settings that can affect what, if anything, is previewed from your WhatsApp messages.

WhatsApp has its own settings:


Tap on WhatsApp
At bottom right tap on Settings
Tap on Notifications
Configure your settings to your liking.


Your iPhone also has settings for Notifications. To access these, go back to your Home screen and go to Settings > Notifications. Here you can configure settings as a whole and also by individual apps.

What you're wanting to do is essentially the opposite of this question, so it may be useful for you to read that as well.