Imām Ibn al-Jawzī (d. 597/1201) summarized the scholars' opinions in his book "Zād al-Masīr" as follows:

1. Al-Sāmirī was from a people who worshiped cows, so this belief remained in his heart. [Ibn ʿAbbās]
2. The Children of Israel passed by a people who were devoted to their idols and they found this appealing. At the time, they asked Moses to make an idol for them and he rejected their request, so during Moses' absence, al-Sāmirī made them a calf, having seen how much they were drawn to that. [Ibn Zayd]

What was the reason that the people of Moses took the calf as a god?

Imām Ibn al-Jawzī (d. 597/1201) summarized the scholars' opinions in his book "Zād al-Masīr" as follows:

1. Al-Sāmirī was a goldsmith, so he crafted the calf and cast a handful of earth into (the melting pot) (see v. 20:96). [ʿAlī, Ibn ʿAbbās]
2. They dug a pit and threw into it the jewelry of the people of Pharaoh and their borrowed items to purify themselves from it. Al-Sāmirī then cast a handful of earth into it, and it became a calf. A report from Ibn ʿAbbās states that it became flesh, blood, and a body. Al-Sāmirī then told them, "This is your god and the god of Mūsā who has come, but Mūsā lost his way." So they worshipped it and danced around it.