There were jewels in the Muslim public treasury. Uthman divided the jewels among his daughters and wives. The Muslims became angry. They began talking against Uthman's bad behaviour.
Uthman went on with his corrupt policy. One day, he went up the pulpit and addressed the people:
We'll take whatever we need from the Public Treasury in spite of all people.
Imam Ali bin Abu Talib became sad when he heard Uthman's words. Ammar bin Yasir aged 90 stood up and said the word of truth:
By Allah, I'm the first man to prevent you from that.
The Caliph became annoyed and said:
Bin Yasir, how dare you say these words before me!
Uthman ordered his guards to arrest Ammar. The guards respected neither Ammar's old age nor his friendship to Allah's Apostle [s]. They drew him into Uthman's room. They chained his hands and legs.
Then the Caliph came and began hitting Ammar on the belly till he became unconscious. Some Muslims came and carried him to our Master Muhammad's wife, Umm Salama's house.
Ammar remembered the days of torture in Makkah. He could endure as many times as what Uthman did because he was a young man. But today he was unable to endure Uthman's torture because he became an old man.
Umm Salama felt pain when she saw Ammar in that bad condition. Yet Ammar said:
This is not the first day when we suffer from torture for Allah.
source : sibtayn