Is the particle "fa'" in "fa-labitha" in the verse "But Satan made him forget the remembrance of his Lord, so he remained in prison for some years" a causal particle, and that the reason for Joseph's remaining in prison was the guile of Satan and not a punishment from God?

The exegetes differed regarding the pronoun in the word (فأنساه - fa-ansāh - so he made him forget), whether it refers to Yusuf or to the cupbearer. Ibn Kathir and other scholars favored that it refers to the cupbearer. The reason given for the forgetting was that Satan was keen for Yusuf to remain in prison. This delay had a great wisdom, for in prison there is self-discipline, and Yusuf gained a high status through his knowledge and virtue, whereas if he had been released through the cupbearer's intercession, he would not have attained that. Al-Hafiz Al-Hakami said: "Likewise, Yusuf's virtue was not manifested to the worlds except through knowledge and wisdom." So, Yusuf's stay in prison was due to Satan making the cupbearer forget, for a divine wisdom. Allah disciplines His servants through decrees, even if they sometimes involve pain. Ibn Kathir said: "The one who was enjoined forgot to mention his lord concerning that, and it was among Satan's stratagems so that the Prophet of Allah would not be released from prison. This is the correct view, that the pronoun in His saying: {so Satan made him forget the mention of his Lord} refers to the survivor." Satan's stratagem was evil in his view due to his ignorance of the consequences, while Allah alone knows the unseen, and Satan's stratagem is weak. Satan wanted to imprison Yusuf, but Allah decreed that for him for a wisdom whose decree cannot be averted.