Why does it say "Ki Chinam"?
Radak #1: There was no theft in my hand (they had no reason to do so).
Radak #2: I do not curse them without reason, but they pursued me without reason.
Malbim: It was groundless, for I did not do evil to them.
What is the meaning of "Tamnu Li Shachas Rishtam"?
Radak #1: They dug a pit, and covered its mouth with a net 1 , so I would pass over it and not sense it, and fall inside. Trappers do so. They make pits and cover them with nets and earth, so Chayos will not sense them.
Radak #2: It is Shachas and Rishtam. Shachas is the cavity - "Ad Yikarei la'Rasha Shachas" (94:13). Also the grave is called Shachas; it is dug out.
Radak #3: Also Shachas is an expression of a net - "Nilkad bi'Shchisosam" (Eichah 4:20). It is like Shisa (Bava Kama 117a), just there the Ches is omitted; guttural letters are sometimes omitted 2 . Shachas is Samuch to Rishtam (even though both mean net) to show their great efforts to trap him, just like "mi'Tit ha'Yaven" (40:3 is Samuch, even though they are the same) and "Admas Afar" (Daniel 12:2).
Malbim: Trappers set a net around the opening of the pit.
Radak: Also Shusa (Bava Kama 39a) is 'word', just the guttural letter Ayin is omitted; the Targum of "va'Ysaper" (Bereishis 24:66) is v'Ishta'ei.
What did they dig for his Nefesh?
Rashi: A pit for him to fall in it. Radak - Nafshi is 'my body.'
Radak: Whatever strategies and pretexts they could plot to trap me, they did.
