Today’s saying 20: The Devil sometimes speaks the truth
Possible interpretation: 1) Sometimes what Satan says is true, to make us more ready to believe his lies. 2) Don’t believe everything at face value. Be aware that liars can use the truth to trick us.
Note: devil (noun): (in Jewish and Christian belief, usually “the Devil”) the chief evil spirit or Satan | truth (noun): what is factual; what is in accordance with reality | Compare The devil can cite Scripture for his purpose | Shakespeare may be alluding to this proverb in Macbeth (c1604) when Banquo says: “What, can the devil speak true?”