There were problems arose due to the ambiguity and silence of Al-Quran and Sunnah in both ancient and modern times and these problems were successfully solved through the concept of Urf and Maslahah Mursalah. It means that sometimes, the Al-Quran and Sunnah was silent about particular issue, where it is not explicitly and directly mentioned in both the sources and there is no indication on how to solve the issues in the Al Quran and Sunnah. This is where the Muslims need to derive from the secondary sources such as ‘Urf (Custom) and Maslahah Mursalah (Public interest). Both Urf and Maslahah had contributed to the progressiveness of Islamic law. In relation to this, Muhammad Firdaus (2002) suggested that ‘urf with its dynamic characteristics, is one of the social phenomenon and always in line with the people’s needs and this sometimes changes the available pattern of maslahah which need a new consideration for new legal ruling. Thus, the functions of ‘urf and maslaha indicates for establishing a legal ruling are clear in this modern and complex world. The legal rulings of both Urf and Maslahah Mursalah does not abrogated in the Holy Quran and Sunnah. However, the prophet and his companion showed the permissibility of using urf and maslahah mursalah in providing legal injunction. For example, one of the hadith on the practice of using birth control during the period of Prophet and his companion “We used to practice azl (contraception) during the lifetime of Prophet Muhammad while the Quran was being revealed” . This signifies that the prophet accept the customs of using birth control for his companion that doesn’t want any children.” Urf and Maslahah not only applied in ancient times, they are also used in modern era to solve problems that are related to Islamic Law and there are a few examples which Urf and Maslahah had solved the problems arose in Islamic Law.