What are the sources of Islamic Commercial Law?

Quran, and Sunna are the main sources. The Ph

rophet صلى الله عليه وسلم taught these revelations to his  students (companion) and they -in turn- taught it to their students تابعين . Now those relayed these teachings to the famous  scholars. These scholars wrote the islamic jurisprudence ( fiqh). The  major ulama have traditionally four schools although there are many scholars but the mostly followed were the four schools of Imam Abu Haneefa, Imam Malik, Imam al Shafeie, and Imam Ahmad.

This whole process took place during  the peak years of Islam (the purest of centuries). This process follows a very systematic and scientific coding for classifying the trustworthines and competence of all peole involved.

i can go on but 

Primary Sources: Quran and Sunnah

Secondary Sources: Ijma, Ijtehad, Qiyas and Urf.

The Holy Qur'an

The Sunnah Prophet MuHammad Sallal-Laahu ^Alayhi Wa Sallam

The Consensus of the Scholars (Ijma^)

The Ijtihad of the Scholars who have the rank of Ijtihaad (Examples: Imam Malik, Imam AHmed, Imam Ash-Shafi^y and Imam Abu Haneefah)

Al Quran , And  the sunnah of Prophet Mohammad (SAW)

QURAN & SUNA ARE THE MAIN SOURCES OF ISLAMIC COMMERCIAL LAW.

1- Quran

2- Sunnah

3- Ijma (consensus)

4- Qiyas (Analogy)

Principally, Quran and also Sunnah Prophet MuHammad (S.A.W)

The answer will be so long >>

but we can summarize it in 4 points 

1- Quraan   2- Sunnah    3- Ijma which means the agreement of Islamic scholars in some new actions , under the role of Quraan and Sunna       4- Ijtehad    5- Qiyas

Quran, and Sunna are the main sources. There is however ijtihad, ijma , urf among others.

Note

since quran and sunnah are the major sources, other sources are only referred to only in circumstances where quran and sunnah are silent.

sunnah in this context is used in refernce to the acts, words and silent approvals of prophet muhammad [peace be upon him]

Islamic Shariat Law directs the transactions of Islamic Commerce