How are "She'ol va'Avadon Neged Hashem"?
Rashi: Everything in it is revealed to Him.
R. Yonah: Hashem investigates kidneys and the heart. Therefore, one should be ashamed to have thoughts of sin in his heart and hatred of rebuke. He should purify it from the abominations of the Yetzer, in front of Hashem, who constantly scrutinizes it.
Malbim: This opposes those who say that Hashem does not know people's thoughts, whether because they were deep and very hidden, or because they change [rapidly], like a raging river. [They say that] Hashem cannot increase or change knowledge. The verse refutes them. She'ol is deeper and more hidden than the heart, and Avadon is formless matter that constantly receives new forms. Even so, it is Neged Hashem, and He knows its depths. So He knows people's hearts!
What is the meaning of "Af Ki [Libos Bnei Adam]"?
Rashi: All the more so [they are in front of Hashem].
R. Yonah: The Nefesh is Ne'etzeles ('copied') from [Hashem's] honor. "Eretz Eifasah" (Iyov 10:22, i.e. the dark land) is from Yesod he'Afar; it and all in it are revealed to Hashem. Also hearts, which are hewn from Kodesh, Hashem examines them - "Ner Hashem Nishmas Adam Chofes Kol Chadrei Veten" (Mishlei 20:27). This is an esteemed warning to examine the chambers of the heart, for Hashem examines them. Therefore, one should be ashamed in front of Him.
Malbim: Refer to 15:11:1:3.
