How to hide text message preview?
I tried this on my Nexus 6P and Android 6.0.1 version

Under "Sound &amp; notification" -> "Notification" tab


Set "When Device is locked" to "Hide sensitive notification content"
App Notifications ->


Select "Messenger" (or the app which you want to hide notification).
Disable the option "Allow Peeking".



This worked for me.