1)
Why did they say "Sheker"?
1.
Rashi: This is false. You are hiding what he told you. Radak - he told you a secret.
2)
What is "ka'Zos vecha'Zos"?
1.
Malbim: The primary message was to anoint him king. He also mentioned the command to wipe out Beis Achav.
