1)
How does Hashem annul the cunnings' thoughts?
1.
Malbim: They are not able to harm people as they intended.
2)
Why does it add "v'Lo Sa'asenah Yedeihem Tushiyah"?
1.
Rashi: They will not do their intended counsel. Malbim - e.g. a verse testifies about Achitofel that his counsel was like asking the Urim v'Tumim. Had Avshalom heeded it, he would have killed David. Hashgachah caused that it was not done.
2.
Ibn Ezra: They will not do like their Chochmah [intended].
3.
Devar Eliyahu: It is help in counsel. "Yedeihem Tushiyah" is counsel via another.
