Hajjaj ibn Yusuf was an intelligent and tough ruler. Al-Hajjaj bin Yousef played a crucial role in the selection of military commanders. He instilled discipline in the soldier ranks which led to the successful expansion of the Islamic empire to its farthest extent. Among these generals was the teenaged Muhammad ibn-Qasim, who in 712 was sent to Sindh in Pakistan and Qutayba ibn Muslim who was sent to conquer Turkestan, which he did. Al-Hajjaj’s most successful general was Musa ibn Nusayr, who consolidated control over North Africa and sent Tariq ibn Ziyad to conquer Spain.He ensured all important records were translated into Arabic, and for the first time he convinced caliph Abd Al-Malik to adopt a special currency for the Muslim world. This led to war with the Byzantine Empire under Justinian II. The Byzantines were led by Leontios at the Battle of Sebastopolis in 692 and were decisively defeated. Here is an excerpt in Urdu from his speech to people of Kufa. I have taken it from a textbook on History of Islam.