Umar al Khattab was reported as seeking for  protection of Allah from a munafiq who understands religion (‘alim).

When asked by the companions, “Is there a munafiq who is also alim, O Amirul Mu’minin?”

He answered, “Yes. He is whose tongue is ‘alim but the heart is jahil (ignorant)”

A munafiq says but practices not. He is who Allah gives His warning in the Quran,

“O you who have believed, why do you say what you do not do? Great is hatred in the sight of Allah that you say what you do not do.” (61:2-3)

~copy~