Why did she say three matters, all of which begin with "v'Atah"?
Malbim (26, 27): There are three reasons to take vengeance; she refuted them. (a) Naval is Mored b'Malchus - she refuted this. 1 (b) Others should not do like he did. Against his will, Naval did what you wanted (you received his food)! (c) You will take by force what is proper for your youths. I already sent to you!
Radak: David was not publicized to be king, and Sha'ul was still alive. Malbim - also, even if you have the law of a king for this, it is improper to avenge your own honor.
Who stopped David from murder, and how
Radak: "Who stopped you" pertains to "Chai Hashem". Rashi - He sent me to stop you.
Why does it say "mi'Bo b'Damim"?
Megilah 14b: She spared David from sinning with Dam Nidah and killing Naval. She revealed her thigh 1 , and he asked to have relations with her. She showed Dam Nidah to him. He asked, do we inspect blood at night?! 2 She said, do we judge capital cases at night?! He said, he rebelled against the king; he need not be judged. She said, Sha'ul is still alive, and you are not known to be the king. 3
Maharsha (Megilah 14b): This refers to two Aveiros for which one is Chayav Misah - a married woman, and murder.
Maharsha (14b): She was three Parsa'os away from David at the time and was unaware of his presence. Iyun Yakov (14b) - it was an Aveirah Lishmah. She aroused his desire so that he would heed her and not kill Naval. (It was a sin, for Isurei Arayos are not permitted for Piku'ach Nefesh. -PF) Salmas Chayim, Inyanim Shonim 193 - he had to see [blood on] her thigh to rule about Nidah. (Even if she would not consent to Bi'ah, she had to show it to a Chacham to rule about it. However, if she knew that we do not inspect blood at night (and merely intended to reply, do we judge at night?!), it would suffice to tell him that she has a question about blood, without showing him! - PF)
Why was he concerned for Nidah, but not for Eshes Ish? Radvaz (7:29) - David mistakenly thought that since Naval was Mored b'Malchuso, all his property, including his wife, belongs to David in Naval's lifetime. He erred; a wife needs a Get. Or, one is Mekadesh according to Rabanan's intent; they uprooted Kidushin of one who will be Mored b'Malchus. It is better to say that Avigayil was merely Naval's Pilegesh; there was no Kidushin. Also refer to 25:44:1:3.
Aderes Eliyahu (2:7): We appoint a leader over the Tzibur only after consulting the Tzibur; this is why Moshe said (Shemos 35:30) "Re'u
What is the meaning of "v'Hoshe'a Yadcha Lach"?
Rashi: He saved you from taking vengeance yourself, for which you would be punished.
Why would David be punished had he killed Naval? Naval was Mored b'Malchus!
Refer to 25:26:1:1*.
Why should David's enemies be like Naval?
Rashi: She had Nevu'ah that he would not live long.
Radak: He has no power to harm you.
Why did she say "Oyvecha" and "ha'Mevakshim El Adoni Ra'ah"?
Malbim: Oyvecha seek to lower your honor. Ha'Mevakshim seek to kill you.
