Surah an-Nisa ayah 105 establishes the following rulings:
1. The Prophet sallAllahu aalyhi wa sallam had the right to arrive at his judgment in situations not covered by an explicit authority given in the Qur’an. In situations of major importance, there were many decisions he took by his ijtihad.
2. The second rule that emerges from here is inseparably linked with the authenticity of ijtihad. It means that, in the sight of Allah, an ijtihad can be considered trustworthy only when it is based on and is deduced from Qur’anic principles and the clear authority of its text. Simple opinions or views are not trustworthy, nor can they be termed as Ijtihad in the sense recognized in Shari’ah.
3. The third rule of guidance we get to know is that the ijtihad done by the Prophet sallAllahu aalyhi wa sallam was not like that done by Mujtahid Imams where the probability of an error of judgment always remains. As for the Prophet sallAllahu aalyhi wa sallam, when he took a decision on the basis of his ijtihad any possible error in the judgment would always stand corrected by Allah subhanahu wa ta’ala. Therefore, when he took a decision based on his ijtihad and nothing against it came from Allah subhanahu wa ta’ala, then, this was an indicator that the decision taken finds favor with Allah and is correct in His sight.
4. The fourth rule of guidance we come to know is, what Rasoolullah sallAllahu aalyhi wa sallam understood from the Qur’an was nothing but what Allah subhanahu wa ta’ala had Himself made him understand. A possibility of misunderstanding just did not exist there. This is contrary to the case of other Ulema and Mujtahidin whose understanding of the Qur’an cannot be attributed to Allah subhanahu wa ta’ala in the sense that it was what Allah had told them. This is why when someone said to Umar radhiAllahu anhu, “Decide as Allah shows you to.” He scolded him by saying, “This is special to the Prophet of Allah sallAllahu aalyhi wa sallam”.
5. The fifth ruling we deduce from here is that pursuing or advocating a false case of a false claim or to second or support them is forbidden.