Will Naval speak in the future?
Rashi: Yedaber is present tense.
What evil does he do?
Rashi: He gathers evil thoughts, e.g. "Asah Li Es ha'Chayil ha'Zeh" (Devarim 8:17).
Radak: He speaks foully, and thinks in his heart how to do evil, until he does so.
What is "La'asos Chonef"?
Rashi: He plans how to do flattery [Radak - until he flatters in the end].
Malbim: These are deeds in order to get haughty, or for another benefit not l'Shem Shamayim.
What do we learn from "u'Ledaber El Hashem To'ah"?
Radak: Because he says that Hashem does not oversee people, he steals when he can, for he says that there is no judgment; Hashem does not see the land. He fears only people.
Malbim: He speaks false and deceiving beliefs.
What is the meaning of "Leharik Nefesh Ra'ev"?
Radak: Aniyim, who are hungry, usually have no helpers. The Naval empties their Nefesh, i.e. he steals their food. It is as if he empties their Nefesh and takes it out. Similarly, he steals their drinks and causes them to lack.
What is the meaning of "u'Mashke Tzamei Yachsir"?
Rashi: He steals from the poor.
Rashi citing Targum Yonasan: Divrei Torah, which are like water for the thirsty, he considers them worthless.
Radak: Refer to 32:6:5:1.