What is the meaning of "Yigmor Ba'adi"?
Rashi: He will agree via my request.
Radak: Like He began to benefit me, so He will complete His Chesed on me.
Malbim: This is one of three reasons why I trust in His salvation. (a) He will finish what He began to save - "Lo Adam Hu Lehinachem" (Shmuel I, 15:29). This is due to His honor, lest there be Chilul Hashem. Also refer to 138:8:2:2, 138:8:3:3.
What is the meaning of "Hashem Chasdecha l'Olam"?
Radak: "Hashem" calls out to him. Your Chesed will be with me forever.
Malbim: I trust in His salvation due to His Chesed. It is l'Olam; it does not depend on deeds of the recipients.
What is "Ma'ase Yadecha"?
Rashi: The Beis ha'Mikdash, about which it says "Konenu Yadecha" (Shemos 15:17).
Radak: It is me. You made me, raised me and made me king. "Al Teref" (do not cease Your Chesed from me).
Malbim: (It is me.) Do not slacken from me, just like a father does not slacken from his son. This is close to Midas ha'Emes - after He created a matter, He is obligated from Emes of His promise not to slacken from helping it.
