[12]. Here is an explanation of the reason behind this great favour: by way of calling them to Islamic Monotheism.
[13]. The favour of guidance to worshipping none but Almighty Allāh without associating any partners with Him in worship.
Faith is an honor, not a heritage. Joseph inherited the message, not privilege — he lived its principles even in prison.
Islamic Monotheism is the core of every prophetic mission.
[14]. That is, they are heedless of this great favour and do not believe and worship only Allāh and Him Alone.
Gratitude sustains faith. When people stop thanking Allāh, they easily fall into shirk (associating others with Allāh in worship).
True gratitude is not in words only but in actions as well and in heart. The thankful heart sees faith itself as the greatest blessing.