Why does it mention people who knew Sha'ul from before?
Malbim: Prophecy requires (a) 'Natural' preparation, that his mix (of bodily powers) and power of Dimyon 1 are proper for it, from the womb; (b) Preparation via choice, i.e. isolation, separation, Taharah, Kedushah...
Perhaps this refers to ability to contemplate intangible matters. (PF)
Why did they say both "Ben Kish" and "Sha'ul"?
Chomas Anach: Kish's father had great merit (refer to 9:1:1:2). Why didn't Kish merit prophecy?
Malbim: Sha'ul lacked the two preparations needed for prophecy (refer to 10:11:1:1). People thought that natural preparation must be from the father; this is more common if the father was a Navi (Kish was not). And beforehand, Sha'ul had not prepared himself; he engaged in matters of his father's house.
