'Umar ibn al-Khattab

'Umar was a strong, quick-tempered man of Quraysh, and harsh to the early Muslims. According to Ibn Ishaq's account, he set out one day with his sword to kill the Prophet.

On the way, he was given some news: his own sister Fatimah and her husband had become Muslim.

He burst into their house and struck his sister. Seeing her blood, he softened. He asked to read what they had been reciting: the opening of surah Ta-Ha. Then he went straight to the Prophet and accepted Islam.

That is one telling. Ibn Ishaq also records a second account, in 'Umar's own words, in which he was moved by hearing the Prophet recite at the Ka'bah. After that, Muslims began to pray openly at the Ka'bah.

A few lines of the Qur'an turned 'Umar, a fierce enemy.

In time, the man who had set out to kill the Prophet became the second caliph. 'Umar oversaw the conquest of Syria, Iraq, Egypt and Persia.

He also built a state. He set up a treasury and salaries, appointed judges, and dated the Islamic calendar from the Hijrah.

Yet he was famous for plain living: patched clothes, simple food. Well-known reports tell of him walking Madinah at night to find people in need, and carrying flour on his own back to a hungry family.

'Umar held great power, and wore patched clothes.

Then came Jerusalem. When the city surrendered around 637, its patriarch, Sophronius, asked to hand it to the caliph himself.

So 'Umar travelled from Madinah. He granted the people safety for their lives, property and churches. A later and widely told story says he declined to pray inside the Church of the Holy Sepulchre, so that Muslims would not later claim it.

In 644 he was stabbed while leading the dawn prayer, and died days later. Not every Muslim remembers him the same way. Shi'a Muslims view him very differently from Sunnis, because of his role in the succession after the Prophet.

'Umar guaranteed the safety of Jerusalem's churches.