1)
Why does it say "Az Yashuvu"?
1.
Radak: When my enemy will turn back...
2.
Malbim: After I saw that on the day that I call to Hashem, He immediately turns my enemy back. After David prayed this, the Pelishtim who were going after him ceased trying to kill him.
2)
Why does it say "Zeh Yadati"?
1.
Radak: This means b'Zeh Yadati (via this, I will know).
3)
What is the consequence of "Ki Elokim Li"?
1.
Radak: My enemy will turn back and fear me, for I will call to Hashem and He will answer me.
2.
Malbim: He has special Hashgachah over me. Refer to 56:10:1:2.
