Counting From the Hijrah

As the lands under Madinah grew, 'Umar gave them the structures they needed. He was the first to be called Amir al-Mu'minin, Commander of the Believers. When letters began arriving without dates, he gathered the companions to choose a starting point for the years; they counted neither from the Prophet's ﷺ mission nor from his death, but from his arrival in Madinah (Sahih al-Bukhari 3934). So the Hijri calendar began.

He set up the diwan, a register of the Muslims and their stipends from the public treasury, ordered by precedence in Islam. The historians report that he began with the Prophet's ﷺ family — his uncle al-'Abbas, then Banu Hashim — gave the Mothers of the Believers a generous share, and placed his own clan where its standing fell, not at the top.

In Ramadan he came into the mosque and found people praying in scattered groups, so he gathered them behind one reciter, Ubayy ibn Ka'b. Seeing them later, he said: "What a fine new practice this is" (Sahih al-Bukhari 2010). For himself he took from the treasury only what an ordinary man would need, and likened his position to that of a guardian over an orphan's wealth: if he had enough he took nothing, and if in need he took what was fair.