1)
Why does it say both "Kol Yemei His'halachnu Itam" (verse 15) and "Kol Yemei Heyoseinu Imam"?
1.
Malbim: Sometimes the flock grazes, and sometimes it enters the pens when the pasture is finished. At the latter time, it need not be guarded; David's men did not harm us verbally or monetarily. When grazing, the flock must be guarded; they helped us; they were a wall of protection.
