# You know this
Possible meanings are 1) "Know this" is a command to pay attention to what I am about to write or 2) "You know this" is a statement saying that I am about to remind you of something that you already know.
# Let every man be quick to hear, slow to speak
These sayings mean people should first listen intently, and then consider carefully what they say.
# slow to anger
"not get angry quickly"