When will he speak in Hashem's Edos?
Radak: When you will help me to reach the Emes.
Why will he not be ashamed?
Radak: If they will challenge me, I will defeat them with Emes. Other kings engage in royal affairs, and when they see me engage in Torah, they challenge me.
Orchos Tzadikim (Sha'ar ha'Bushah DH u'Mi): One must not be ashamed to ask what he does not know 1 .
Mesilas Yesharim (Perek 5): Even though most kings engage in and talk about grand matters 2 and pleasures, and David, who was also a king, seemingly it would be shameful to speak matters of Musar and Torah when among them. He was not concerned for this, and his heart was not enticed to their follies, for he already attained the truth.
Mesilas Yesharim (Perek 20): One must guard all Mitzvos with all their details, no matter whom he is in front of, and not fear or be ashamed. 'Be brazen like a tiger...' (Avos 5:20).
Malbim: Before he repented, he was ashamed to speak about the Edos, for they testify that Hashem punishes the Rasha. However, now that I guard the Torah and the Pikudim, and my sin was atoned, I am not ashamed - "Gal me'Alai Cherpah va'Vuz Ki Edosecha Natzarti" (22).
Presumably, he explains that "Melachim" refers to Chachamim, like Gitin 62a learns from "Bi Melachim Yimlochu" (Mishlei 8:15). What would David ask from Nochri kings?! (PF)
E.g. of their wealth or military strength. (PF)
