Why does it say "Nafshi Ivisicha [ba'Laylah]"?
Rashi: In my Galus, which resembles night, [I desired] that You do these [judgments in the land].
Radak: With all my strength and desire, I craved for You. When it discusses Yisrael, sometimes it speaks in the plural, regarding the individuals, and sometimes in the singular.
Malbim: "Nafshi" calls out - You, Hashem, that You are my Nefesh! You sustain me, move me and conduct me, like a Nefesh does to the body. Also at a time of darkness and affliction, I desired only You, and I rejoiced in afflictions, for via them Your name is aggrandized. Hashem supervise over him to benefit him at night (times of affliction), when it seems that Ru'ach ha'Olam (Hashgachah Pratis) is in Hester Panim. "Nafshi" applies to night, for when he sleeps at night, he has only Nefesh; the Ru'ach departs, and returns only in the morning.
What is the meaning of "Af Ruchi b'Kirbi Ashachareka"?
Rashi: I supplicate to you for all of this. Why? When your Mishpatim come to the land, You do Mishpat against Resha'im.
Radak: As long as my Ru'ach is in me, I am early to pray to You.
Malbim: You, Hashem, are my Ru'ach inside me. When morning comes and illuminates the night, You are the morning that illuminates and removes darkness due to light. Ru'ach applies in the morning, for when he slept at night, it departed, and returns in the morning. Hashem arouses him in the morning (the time of salvation), his Ru'ach appears (returns) to him.
What is the meaning of "Ki Ka'asher Mishpatecha la'Aretz"?
Radak: Even though Your Mishpatim come upon us, I will not refrain from pursuing You and desiring You, for I see that Your Mishpatim are good. When they come to the land, people of the world are chastised and learn to do justly. These are those that Elokim touched in their hearts. The world exists for them. There will be no grace on Resha'im (10].
Malbim: When Your Mishpatim are seen in the land, "Tzedek Lamdu", for they see that Elokim judges in the land.
What Tzedek did they learn?
Rashi: They learn to justify Your judgments and to thank for Your Midos. They see the sinner stricken and the Tzadik receives good reward.