Reason behind disagreement among Imams Malik, Ahmad and Al-Shafi`y

Q: What are the causes of disagreement in legal opinions among Imams Malik, Al-Shafi`y and Ahmad ibn Hanbal (may Allah be Merciful with them)?

A: All praise is due to Allah Alone and peace and blessings be upon His Messenger, his family and Companions. To commence, there are many causes behind the differences among the Four Imams (Imams Abu Hanifah, Malik, Al-Shafi`y and Ahmad) of jurisprudence and others. Many books have been compiled in this regard as Raf` Al-Malam `An Al-A'imah Al-A`lam by (Part No. 5; Page No. 23)  Ibn Taymiyyah, Al-Tamhid Fi Takhrij Al-Furu` `Ala Al-Usul by `Abdul-Rahim Al-Asnawy, Al-Insaf Fi Bayan Asbab Al-Ikhtilaf by Waliu-llah Al-Dahlawy, Asbab Ikhtilaf Al-Fuqaha' by `Aly Al-Khafif, Al-Insaf Fi Al-Tanbih `Ala Al-Asbab Allaty Awjabat Al-Khilaf by `Abdullah ibn Sayyid, and Bidayat Al-Mujtahid by Ibn Rushd. He mentioned places of agreement in certain issues and then mentioned places of disagreement. He, then, pointed out the origin of disagreement. We will mention some of these causes for you: 1- A word may be homonymous, i.e. It has two or more different meanings as in Allah's saying: And divorced women shall wait (as regards their marriage) for three menstrual periods The word Qur' is a homonymous word that means the period of menstruation and the period of purity after the end of menstruation. Some of the scholars said that the divorced women should count the waiting period according to the periods of purity and others said that they have to count it according to the periods of menstruation. The two groups have proofs that support their sayings. 2- The contradiction among proofs: Jurists may disagree in giving preponderance to one of the proofs over the other when it becomes difficult to combine between them, such as the Hadith that prohibits a person from performing supererogatory prayer after `Asr (Afternoon) Prayer until sunset and the Hadith that prohibits the person who enters a Masjid (mosque) from sitting before performing two Rak`ahs for the salutation of the Masjid. Jurists have disagreed concerning applying the rulings of these two Hadiths upon he who enters a Masjid in a time when it is not permissible to perform Salah. Some of them gave preponderance to the Hadiths that prohibits performing Salah and some of them gave preponderance to the Hadith that asks one to perform two Rak`ahs for the salutation of the Masjid. A certain Hadith may also reach some of them while others do not know it. They may also disagree concerning the abrogation of the Hadith. Fatwa is not a room for detailing such issue. Therefore, we advise you to read the books mentioned above to make use of them (Part No. 5; Page No. 24) if you are a knowledge seeker.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.