"Elohei Masechah Lo Sa'aseh lach". Why does the Torah need to mention it? Why would we have thought that it is permitted?
Seforno: It is a prohibition against turning to a molten idol for financial and personal gains 1 - without actually accepting them as gods. 2
See Seforno, who describes the procedure.
Seforno: Whereas the Torah expects us to turn to Hashem and to Hashem alone for all our needs, as the Pasuk indicates in Divrei ha'Yamim 2, 2:12.
Why does the Torah need to insert the current Pasuk? Why would we have thought that they are permitted?
R. Bachye, Hadar Zekenim and Da'as Zekenim: Following the sin of the Eigel, Hashem is warning them not to indulge in such stupidity to remember again (to remember Midas Rachamim [as symbolized by Matzah] - and not to dabble in Midas ha'Din [as symbolized by Chametz] - R. Bachye). 1 2
Erech Apayim (1, based on the Zohar in Tetzaveh): It is a warning against making an idoatry through anger, since it causes the Holy Neshamah to depart..
R. Bachye: Also Basar be'Chalav - in Pasuk 26 - symbolize Din and Rachamim. See R. Bachye who explains why the Torah therefore inserts it here, and in Shemos 23:19, together with the Isur Chametz.
See R. Bachye who elaborates further.
