The first verse of the Quran revealed to the Prophet was: 'Read!' (96:1) This was the first word which came down from God to the Prophet. The first lesson that the Prophet received from God was to educate himself and increase his learning. The Prophet's Companion Zayd ibn Thabit earlier knew only Arabic, but afterwards learnt four more languages. In the Battle of Badr in 624 AD, Muslims took seventy of their Makkan opponents as prisoners to Madinah. People generally treat prisoners of war harshly, even going to the extent of executing them. The Makkan prisoners of war were literate men as compared to the people of Madinah. The Prophet took this as an opportunity. He made it known that if any Makkan prisoner of war could teach ten children of Madinah to read and write, he would be released from captivity and set free. This was constructive use of prisoners of war. The Makkan opponents were criminals who had shown great hostility to the Muslims. However, the Prophet laid so much importance on education that he allowed imparting of education to Madinah's children to act as ransom for the Makkan prisoners of war. Setting these opponents free was dangerous, as there was threat that they may reorganize and again launch an attack on Madinah. The Prophet here set the example that one should receive education even if it involves taking of risks. Once the Prophet said that one should try to gain education even if one has to travel to China for the purpose. In those times, travel was very difficult. Thus the Prophet meant that even if you have to suffer difficulties, you should try to attain education. In this way, the Prophet promoted education to a great extent. The result was that there developed in Muslim society an atmosphere and culture to learn and educate. In Baghdad, the Muslims established Bayt al-Hikmah (The House of Wisdom) in the eighth century AD. In this centre, several books in Greek, Latin and Sanskrit from all over the world were procured and translated into Arabic.