Today in the era of disruption 4.0, an interesting thing in Indonesia is related to the presence of Crypto Investments such as Bitcoin (digital currency), where which is one of the economic indicators that can affect the global economy. Now business transactions are using online media (digitalization). Therefore, the Indonesian people need legal certainty in utilizing transactions for this crypto investment activity. This study aims to legally analyze crypto investments used for buying and selling transactions in Indonesia from the perspective of Islamic law and creed theory. This study uses the Library Research Method, where the data is obtained by means of a literature study through laws, government regulations, Fatwa DSN MUI, and the theory of creed / testimony / Shahadah. As a result, by referring to the creed theory that Crypto Investments such as Bitcoin have laws that are permitted when used as a medium of exchange. This law only applies to parties who acknowledge and are willing to use it. Meanwhile, Bitcoin as an investment is illegal. However, Crypto as a transaction tool in online trade is a renewable innovation in economic development in Indonesia today. So there is a need for special regulations to use Crypto.

This article describes the policy of the Islamic fiscal management system managed by the state with the aim of improving the people welfare during the Khulafa ar-Rasyidin era. This study uses a normative historical method and an exploratory approach that refers to various relevant literatures and is analyzed qualitatively. This research shows that the culture of the Islamic fiscal management system during the Khulafa ar-Rasyidin era tended to continue the Prophet's culture and development which included a balanced budget policy, as evidenced by the instruments of zakat, ghanimah, kharraj, jizyah, waqf, and others, and distributed for the welfare of society. The policy of managing the Islamic fiscal system is now widely used as a reference for developing a modern fiscal system. This result of this study found that the policy of the Prophet Muhammad regarding on fiscal management was continued by Khulafa ar-Rasyidin, which was a representation of the principles of public spending in the social, political, economics, and security context, whose it was based on the principle of a balanced budget policy. And then, the utilization of zakat, jizyah, kharaj, ghanimah, and waqf instruments as the sources of the state budget at this period, illustrating the dynamics of the caliph's fiscal policy progressively during the Khulafa ar-Rasyidin era, which was succeeded in bringing the Muslims to be in the golden age. Unfortunately, after the fall of the Abbasid Dynasty and continued to the colonialization period, Islamic fiscal policy was also declined.

Fungsi uang berubah menjadi multifungsi. Jenis uang beragam yang utamanya adalah sebagai alat tukar menukar untuk kebutuhan manusia. Pengertian uang secara luas adalah sesuatu yang dapat diterima secara umum sebagai suatu alat pembayaran dalam wilayah tertentu atau sebagai alat pembayar utang dan alat untuk melakukan alat pembeli barang dan jasa. Definisi uang dalam pengertian ekonomi merupakan alat tukar yang dapat diterima secara umum oleh seluruh masyarakat dalam menjalankan proses pertukaran barang dan jasa. Dalam ekonomi Islam, secara etimologi uang berasal dari kata al-naqdu-nuqud. Pengertiannya ada beberapa makna, yaitu al-naqdu yang berarti yang baik dari dirham, menggenggam dirham, dan al-naqdu juga berarti tunai. Kata nuqud tidak terdapat dalam al-Qur’an dan hadist karena bangsa arab umumnya tidak menggunakan nuqud untuk menunjukkan harga. Fungsi uang dapat menentukan aktivitas manusia, uang dapat mencukupi kebutuhan hidup serta memperlancar aktivitas sosial. Uang dapat dilihat dari segi hukum, logika, dan tradisi yang dapat diterima sebagai nilai adanya emas dan perak. Mata uang yang berasal dari bahan kedua logam tersebut tidak dapat dikatakan sebagai mata uang.

Islamic Microeconomics is a branch of economics that examines how individuals conduct economic transactions within the framework of the Qur'an and Sunnah. Imam Abu Ubaid explored this microeconomic problem in his book al-Amwal, while Imam al-Syaibani discussed it in his book al-Alkasb. This magazine examines these two major figures' perspectives on research at the microeconomic level, employing descriptive qualitative approaches, and examining sources from reference journals and books on related themes. Imam Abu Ubaid is a Muslim scholar who is well-versed in the subject. Economic Islam. Many of his ideas were expressed in his many works, the most important of which is Kitab al-Amwal. This book contains Islamic economic principles as a reference in discussions of public finance, whereas Iman As Syaibani in Kitab al Kasb draws a temporary conclusion that work is human productivity that can make a person feel kissed in the world and worthy of worship in achieving Allah SWT's pleasure.