Who are the Keini?
Rashi: They are Yisro's descendants. They dwelled in Midbar Yehudah, south of Arad; they went to Ya'avetz to learn Torah. Arad is Amalek - "ha'Kena'ani Melech Arad Yoshev ha'Negev" (Bamidbar 21:1) was Amalek - "Amalek Yoshev b'Eretz ha'Negev" (Bamidbar 13:29).
Why does it say that Keini was amidst Amalek? They dwelled with Bnei Yehudah is Eretz Yehudah (Shoftim 1:16)!
Radak: Later, all or some of them went to dwell with Amalek. They dwelled in tents, and traveled from place to place, according to where they were able to dwell.
Malbim: Keini was grazing their flock in the valley. Sha'ul told them to separate from where the war will be.
What is the meaning of "Osifcha"?
Radak, Malbim: This is Hifil, from the root Asaf, like "Ovidah Ir" (Yirmeyah 46:8). It means finishing off.
What Chesed did Keini do for all of Yisrael?
Rashi: Moshe, Aharon and the elders benefited from Yisro's meal. 1 It is attributed as if he did Chesed for all of Yisrael.
Radak: This was Yisro's counsel. It is considered as if his descendants did the Chesed with all of Yisrael - "Kol ha'Am ha'Zeh? Yavo v'Shalom" (Shemos 18:23).
Radak citing Vayikra Rabah 34:8: Yisro said "Kir'en Lo v'Yochal Lechem" (Shemos 2:20). One who does Chesed for one of Gedolei Yisrael, it is attributed as if he did Chesed for all of Yisrael.
Yisro took Olah and Zevachim to Hashem, and Aharon and all the Zekenim ate with him. (Shemos 18:12). Perhaps it is understood that also Moshe ate. Or, Yisro fed Moshe previously (Shemos 2:20). This is slightly different than our version of the Midrash. Refer to 15:6:4:3. (PF)
