We know for one, that Muhammad SAAWS never uttered words out of his own desire, except that which was divine revelation to him from Allaah.
He had knowledge of all the hypocrites we know because of the famous incident when the Prophet SAAWS entrusted the names of all the hypocrites to Huthaifa:
http://en.wikipedia.org/wiki/Hudhayfah_ibn_al-Yaman#The_Hypocrites (dont believe everything on this page, but that part is correct InshaAllaah)
As you can see Muhammad SAAWS entrusted the names of these people with the one he thought would best keep a secret no matter what. What does this teach you?
Of course eventually it becomes apparent. As with the case of Abdullaah ibn Salool, all the Muslims of Madinah realized he was a munaafiq after his efforts to upset the plans of the Messenger SAAWS. And yet, you will never find an account when the Prophet SAAWS pointed him out. In fact it was Allaah who testified to the fact that Abdullaah was a munaafiq:
http://islam.thetruecall.com/modules.php?name=Quran&func=goto&gotoparam=63:1-8&at[]=999&at[]=5
Verses 1,5, and 7 were specific things that Abdullaah had done, so it was abundantly clear to the believers who he was.
What we learn from this is:
The attributes of a munaafiq can be found in the Quraan and this hadith (among many others):
Narrated 'Abdullah bin 'Amr: Allah's Apostle said, "Whoever has (the following) four characteristics will be a pure hypocrite: "If he speaks, he tells a lie; if he gives a promise, he breaks it, if he makes a covenant he proves treacherous; and if he quarrels, he behaves in a very imprudent evil insulting manner (unjust). And whoever has one of these characteristics, has one characteristic of a hypocrite, unless he gives it us."
The hadith means that if a person were to possess all of these 4 characteristics he would be a hypocrite. Yet it is is possible to possess one of them only and not be a pure hypocrite, but you would have a quality of the hypocrites. I think we might be surprised to find out that we possess one or more of these... May Allaah not make us of the hypocrites!
If you discover a person to have one or more or all of these attributes in an individual, it is best you advise them. If they feel remorse and regret Alhamdulilah. But if they do not try to improve then it is a problem.
That doesn't mean you go and start spreading information about them! From the wisdom of the prophet SAAWS was to never disclose the names of the hypocrites when he was
100% certain. What about us when we judge based on what we see alone? It is also best for all of us to conceal the faults of muslims.
Of course Muhammad SAAWS did not treat them as he would other muslims. Especially when it came to sharing battle plans etc with them. But he also did not rebuke them nor did he insult them personally. Such was his character. And in fact, when he prayed Janaza (funeral prayer) over Abdullaah Allaah immediately revealed the verse which means:
And do not pray [the funeral prayer, O Muhammad], over any of them who has died - ever - or stand at his grave. Indeed, they disbelieved in Allah and His Messenger and died while they were defiantly disobedient.
[9:84]
And Allaah knows best.
