Why did Sha'ul go to his house?
Radak: He saw that he was not acceptable to all of Yisrael. [Malbim (27, citing Mahari) - it was proper that the people agree to Hashem's choice. he saw that a minority disgraced him (verse 27), therefore] he did not conduct yet with the law of a king. 1
Malbim (27): After Sha'ul saved Anshei Yeavesh Gil'ad (Perek 11), then all accepted him, and they went to Gilgal to be Mechadesh the kingship.
What is "Asher Naga Elokim b'Libam"?
Rashi citing Targum Yonasan: Men who fear sin, that was put in their hearts fear in front of Hashem. Radak - Bnei Beliya'al (verse 27) supports this. 1
Radak: Hashem put in their hearts to be pleased with Sha'ul.
I.e. these words imply that they did not fear Hashem. According to Radak's own Perush, their dissatisfaction with Sha'ul suffices to shows that Lo Naga Elokim b'Libam. (PF)
