Why did he say "Keli Atah"?
Radak: You are my Rock and strength when I flee, for I have no escape or support other than You.
Malbim: This is why I seek only You.
What is the meaning of "Ashachareka"?
Rashi: I will seek You. This is like "v'Shichartani v'Eineni" (Iyov 7:21).
Radak: I will pray to You every morning when I am moved from place to place.
Why did he say "Tzam'ah Lecha Nafshi"?
Rashi: I thirst and desire to come to You in Your house of Tefilah.
Radak: I desire to be in Eretz Yisrael, secure, so I can come to Mekom ha'Kodesh - Kiryas Ye'arim, where the Aron was, or Giv'on, where the Ohel Mo'ed was. All who sought Hashem came to [one of] these two places; Chachamim were frequent there. David desired to be among them and learn from them, like one who is thirsty in a desert.
What is the meaning of "Kamah Lecha Besari"?
Rashi: It is an expression of desire. There is nothing like this in Tanach. Radak - Tzam'ah refers to the Nefesh, and Kamah to the body. Thirst is the greatest Ta'avah (desire), and the intellectual Nefesh has the ultimate Ta'avah for Chachmah and closeness to Hashem. The Basar, i.e. the body with Ru'ach Chayim, desires to dwell in a secure place.
Mesilas Yesharim (Perek 7): What is most accepted in Avodas Hashem is desire of the heart and yearning of the Neshamah. David glorifies himself about his good portion.
Malbim: Even though I am in a dry desert, where the flesh and Nefesh thirst for water, my thirst is not for water, rather, for You!
What is "b'Eretz Tziyah"?
Rashi: It is a Midbar.
What is "Ayef"?
Radak: It is like thirsty - a land thirsty for water. The same applies to "k'Eretz Ayefah" (143:6). It is a masculine form, for "Eretz" can be masculine 1 , e.g. "v'Lo Nasa Osam ha'Aretz" (Bereishis 13:6).
The previous word "Tziyah" is feminine; it is a noun (a dry Midbar), and not an adjective. And even if it were an adjective, the same noun can have masculine and feminine adjective in the same verse, e.g. "v'Ru'ach Gedolah v'Chazak" (Melachim I, 19:11).
