Why does it repeat that he returned it to his mother? Verse 3 already said so!
Rashi (3): Before, he only said to return it; where it is, it is already in your Reshus.
Radak (3), Malbim: He returned it 1 , and she returned it to him to make a Pesel. He did not want to, and returned it to her again.
Malbim: He returned it immediately; this shows that he feared Hashem.
She gave 200 to the smelter. What happened to the other 900?
Radak (3): His wage was 200. The Pesel was made from the other 900.
Malbim: Michayhu explained to her that her Hekdesh did not take effect, for the money was not in her Reshus (Bava Kama 70a). Due to his words, she used only 200 for the image.
Why does it say that the image was in Michayhu's house?
Malbim: Even though he did not serve it yet, he transgressed the Lav "Lo Yihyeh Lecha Elohim Acherim Al Panai" (Shemos 20:3) for leaving it in his house.
It says in Sanhedrin (103b) that Michah passed the Yam [Suf] with the idolatry. Pesel Michah was made later, in Eretz Yisrael!
Rashi (103b) - Michah had with him the name that he would later used to make the golden calf (refer to Shemos 32:4:2:1***).
Yad Ramah (103b): Michah, who would later make the Pesel, crossed with them.
Roke'ach (Perush Az Yashir): Michah did not cross with the idol. Rather, he took coins needed for it. 1
Mishnas R. Aharon (2, p.48, citing the Vilna Gaon): There was a small breach within Yisrael now, which led to Pesel Michah generations later.
He stole the coins from his mother; she returned them, and he did not want to make the idol! Perhaps he crossed with the stolen coins. (PF)
