Para ulama telah mengemukakan dalil berkenaan kepentingan Al-'Urf dan mereka menganggapnya sebagai Shar'an (sah dari sudut syariat) berdasarkan pandangan ulama-ulama terdahulu termasuk:

The ‘Ulamaa have presented evidence in respect to the importance of Al-‘Urf and they considered it to be Shar’an (legitimate) based upon the views of the previous ‘Ulamaa including:

1 – Al-Imam Malik yang banyak membina (atau berdasarkan) hukum-hukumnya di atas amalan penduduk Al-Madinah, iaitu di atas adat kebiasaan Ahl-ul-Madinah dan ‘Urf mereka.

1 – Al-Imaam Maalik who built (or based) a lot of his Ahkaam upon the actions of the people of Al-Madinah i.e. upon the customs of Ahl-ul-Madinah and their ‘Urf.

2 – Abu Haneefah dan murid-muridnya (pengikut) berbeza pendapat dalam sebahagian Ahkaam Ash-Shar'iyah berdasarkan perbezaan a'araaf (adat kebiasaan) mereka.

2 – Abu Haneefah and his students (followers) differed in respect to some of the Ahkaam Ash-Shar’iyah based upon the difference in their A’araaf (customs).

3 – Al-Imam Asy-Syafi‘i telah mengubah beberapa hukum (Ahkam) selepas beliau berpindah ke Mesir, hukum-hukum yang sebelumnya beliau pegang ketika berada di Baghdad. Hal ini didakwa berpunca daripada perbezaan ‘urf (adat kebiasaan) antara kedua-dua tempat tersebut, dan atas sebab inilah beliau mempunyai dua mazhab, yang lama dan yang baharu.

3 – Al-Imaam Ash-Shaafi’iy changed some Ahkaam after going to Egypt which he had previously held whilst he was in Baghdad. That has been argued to be due to the differences in ‘Urf between the two places and it is for this reason that he has two Madh’habs, the old and the new.

4 – Ibn ‘Aabiden menulis sebuah risalah tentang Al-‘Urf dan berkata di dalamnya: “Al-Ma’roof ‘Urfan (yang diketahui melalui adat) adalah seperti Al-Mashroot Shartan (yang disyaratkan melalui syarat), dan Ath-Thaabit (yang ditetapkan/dibuktikan/tetap) melalui ‘Urf adalah seperti yang ditetapkan melalui Nass (teks).”

4 – Ibn ‘Aabiden authored a paper about Al-‘Urf and said in it: “The Ma’roof ‘Urfan (the known by custom) is like the Mashroot Shartan (the stipulated by condition) and the Thaabit (established/proven/consistent) by the ‘Urf is like the established (Thaabit) by the Nass (text)”.

'Urf dalam hakikatnya yang sebenar terhasil daripada pemikiran-pemikiran yang berleluasa dalam masyarakat dan daripada sistem serta undang-undang yang mengurus hubungan-hubungan dalam masyarakat. Oleh itu, pemikiran-pemikiran dan sistem-sistem tersebut telah menjadi adat dan ukuran (kriteria) bagi orang ramai, sama ada mereka menyedari sumber asalnya atau tidak menyedarinya.

The ‘Urf in its true reality results from the thoughts that are prevailing within the society and from the systems and laws that treat the relationships of the society. As such these thoughts and those systems have become customs and measures (criteria) for the people whether they are aware of their original source or are unaware of it.

Oleh itu, 'Urf di kalangan umat Islam, sebagai contoh, lahir daripada pemikiran Islam yang telah diterima pakai oleh masyarakat dan yang telah dirujuk oleh orang ramai untuk membuat keputusan selama berabad-abad. Ini seperti adat yang berlaku berkaitan perayaan, perkabungan dan hari raya. Hal ini kerana kebanyakan adat tersebut berasaskan sebuah nas daripada nas-nas Syariat Islam.

Therefore, the ‘Urf, for example, amongst the Muslims, results from the Islamic thoughts that the society has adopted and which the people have sought to go to judgment to for many centuries. This is like the prevailing customs in respect to celebrations, grief and the Eids. That is because most of these customs are based upon a text from the texts of the Islamic Shar’a.

Sebab perubahan dan penggantian sebahagian adat-adat ini kembali kepada ketiadaan hukum Islam dalam kehidupan masyarakat dan kemasukan beberapa pemikiran untuk menggantikannya, seperti pemikiran-pemikiran yang berkaitan dengan kapitalisme dan komunisme.

The reason for the alteration and changing of some of these customs goes back to the absence of the Islamic ruling within the life of the people and the insertion of some thoughts to replace them like those attached to the capitalist and communist thoughts.