The Change of Kribalah

The change of Kribalah probably occurred around 15 to 16 months after the immigration. This caused a mini crisis, why for many reasons? Firstly because this was the first time that Allah had abrogated a ruling. And this is a detailed topic of usoul al-Firk or the realities of deriving Firk. There is no contradiction in nasq and there's no contradiction in the Quran, there is abrogation.