1 Samuel 14:51

14:51 Kish was the father of Saul, and Ner the father of Abner was the son ¹  of Abiel.

1 Samuel 17:55

17:55 ² Now as Saul watched David going out to fight the Philistine, he asked Abner, the general in command of the army, “Whose son is this young man, Abner?” Abner replied, “As surely as you live, O king, I don’t know.”

[14:51]  ¹ tn 1 Chr 9:35-36 indicates that Jeiel (= Abiel?) had two sons (among others) named Ner and Kish (see also 1 Sam 9:1 and 1 Chr 8:30, where some Greek manuscripts include the name Ner, though it is absent in the Hebrew text). If this Kish was the father of Saul and Ner was the father of Abner, then Saul and Abner were cousins. However, according to 1 Chr 8:33 and 9:39, Ner, not Abiel, was the father of Kish. In this case, Kish and Abner were brothers and Abner was Saul’s uncle. The simplest solution to the problem is to see two men named Kish in the genealogy: Abiel (Jeiel) was the father of Ner and Kish I. Ner was the father of Abner and Kish II. Kish II was the father of Saul. The Kish mentioned in 1 Sam 9:1 was the father of Saul (v.2) and must be identified as Kish II. In this case the genealogy is “gapped,” with Ner being omitted. Abiel was the grandfather of Kish II.

[17:55]  ² tc Most LXX mss lack 17:55–18:5.