Midrasch zu Schemuel I 12:1

(I Sam. 12, 1) One year old was Saul in his reign. R. Huna said: "Like a child of one year, so was he innocent of sin." R. Juda, in the name of Samuel, said: "Why did not Saul's dynasty last long? Because there was no stain on his whole family; for R. Jochanan in the name of R. Simon b. Yehozada, said: 'The chief of a congregation should not be appointed unless a heap of reptiles hang on his back [to whose ancestry some blemish is attached] so that, when he becomes overbearing, we can say to him, 'Turn behind thee.' " R. Juda, in the name of Rab, said: "Why was Saul punished? Because he permitted himself to forego honors due him, as it is said (Ib. 10, 27) But the worthless men said, in what can this one help us? And they despised him, and brought him no presents, etc. And soon after this is written. Then came up Nachash, the Ammonite, etc."