How did He know Efrayim?
Radak: This refers to Yaravam ben Nevat from Shevet Efrayim, who made the calves and separated Yisrael from Avodas Hashem in the Beis ha'Mikdash. I knew his heart ? "va'Yomer Yaravam b'Libo Atah Tashuv?" (Melachim I, 12:26).
Radak: based on Seder Olam 22: Now I know that Efrayim is Mezaneh; they cannot blame their sin on their kings (refer to 5:3:3:1).
Malbim: I, the Navi, know Efrayim, and Yisrael is not hidden from me. I know their nature; my Musar will not help.
How was Yisrael not denied from Him?
Radak: [Yaravam] took counsel with officers of Yisrael. I knew it ? "va'Yiva'etz ha'Melech va'Ya'as Shnei Eglei Zahav" (Melachim I, 12:28).
Malbim: Refer to 5:3:1:3.
Why does it say "Ki Atah Hizneisa Efrayim"?
Rashi, based on Seder Olam 22: Until Hoshe'a ben Elah, the ruin was attributed to the kings, who stopped people from ascending for the Regel. He ceased the guards 1 , and still they did not ascend ? therefore, they were exiled, for now Efrayim was Mezaneh, and they cannot attribute it to their king.
Radak: You, Yaravam, were Mezaneh with the calves, and afterwards Yisrael became Tamei with idolatry. Hizneisa is Po'el Yotzei ? you caused Yisrael to be Mezaneh with Ba'alim.
Malbim: Efrayim is Beis ha'Malchus. It entices the nation to be Mezaneh with the calves. Via this, Yisrael became Tamei through him.
Radak: We learn from "Rak Lo k'Malchei Yisrael Asher Hayu Lefanav" (Melachim II, 17:2).
