Ammar bin Yasir (r.a.)
He was a member of a lonely and poor Yemeni family. This family, which is known as "Family of Yasir" in Islamic history, was subjected to the biggest persecution and torture of the polytheists. There was only one reason for these tortures: The connection of the family of Yasir with Islam. As the number of the Muslims increased, the polytheists were worried more and more. The savage polytheists had nothing but torture to dissuade the believers. They turned mad when they could not dissuade the Muslims.
The heart of Hz. Ammar, the young son of the Yasir family, was full of with the desire of Islam. He wanted to go and see the Messenger of Allah and learn Islam from him. The Prophet Muhammad was in Darul-Arqam, the center of teaching Islam. He told the people about the truths of Islam and taught them the verses of the Quran that were sent down there. Hz. Ammar went directly to Darul-Arqam. He entered into the presence of the Messenger of Allah. He became a Muslim immediately. At that time, the number of Muslims on the earth was no more than the number of the fingers of a hand. According to a narration, Hz. Ammar was one of the first seven Muslims. 
The entire family of Yasir became Muslims. However, they concealed it due to their fear from the polytheists. For, this family came to Makkah from outside. They had to be under the protection of a powerful tribe. The protectors of the family of Yasir were Sons of Mahzum, one of the strong tribes of the Makkan polytheists. This tribe never tolerated Yasir family being a Muslim. They inflicted unimaginable tortures on these people, whom they had agreed to protect. They could accept anything from the family of Yasir, but they could never accept their becoming Muslims. First, they tried to dissuade them by giving them rewards, but when they failed, they started to torture them. They became the first Muslims that were subjected to tortures in the history of Islam.
The three members of the family of Yasir, Hz. Yasir, Hz. Sumayya and Hz. Ammar, were made lie on hot sand in the scorching heat of Makkah and were left hungry and thirsty. The Messenger of Allah (pbuh), who saw these tortures but who could not prevent them, became very sorry and prayed to Allah as follows:
“O Allah! Show mercy on the family of Yasir and forgive them!”
When Hz. Yasir saw the Messenger of Allah, he could not help asking in tears: “O Messenger of Allah! How long will this torture go on?”
The Messenger of Allah consoled them by saying, “O family of Yasir! Be patient! The reward of your patience and perseverance will be Paradise.”
The family of Yasir really showed the example of the highest patience in the history of Islam. They never surrendered to the will of the polytheists.
They fell in love with the light of the Quran. Hz. Yasir protected Islam's glory under torture; he passed away, never surrendering to the oppressors. When his body was crushed under torture, his spirit flew to Paradise as a martyr.
His wife, Sumayya, was at the peak of perseverance in belief. The person who tortured her was Abu Jahl, the biggest enemy of Islam. However, Hz. Sumayya did not heed the pressure of Abu Jahl. Abu Jahl understood the reason for her insistence and perseverance. Finally, he used his spear and martyred her.
Thus, Hz. Yasir became the first male martyr of Islam. And Hz. Sumayya became the first female martyr of Islam. They passed this hard test and sacrificed their lives so that Islam would settle. They attained the eternal bliss by receiving the glad tidings from the Prophet.
Now, it was time for their son Ammar. His mother and father were martyred before his eyes. He felt weak under heavy torture. The polytheistic group wanted Ammar to speak against the Messenger of Allah. They wanted him at least to say that he had given up his belief and to state that Lat and Uzza idols were better than "the religion of Muhammad". Hz. Ammar did not lose his steadiness but there was no other way of being saved. He was either going to be killed or say what they wanted him to say. Hz. Ammar could not decide which one would be better for the elevation of Islam. To say what they wanted him to say was worse than death. He finally fulfilled their wish in order to rejoin the Messenger of Allah. He said with his tongue that he had given up his religion. The polytheists released him.
Hz. Ammar did not say it in his heart, but he was still worried. His heart shivered. As soon as he was released, he rushed to the Messenger of Allah and said, "O Messenger of Allah! I have been destroyed; I have denied my belief." Then, he narrated to the Messenger of Allah what had happened.
The Messenger of Allah asked him, "How is your heart?" He asked whether his heart approved what he had said.
Ammar answered, "My heart is full of belief."
The Messenger of Allah said, "Ammar is full of belief from head to toe. If you are tortured like that again, it is permissible for you to do the same thing in order to get rid of them."
Upon this statement of the Messenger of Allah, Hz. Ammar calmed down and felt relieved. A verse was sent down upon this incident that happened to Ammar. It was stated that a person who was forced to deny his belief though his heart was full of belief would not be held responsible. Thus, Hz. Ammar's belief was confirmed by the Quran. 
Afterwards, Hz. Ammar migrated to Madinah. The Messenger of Allah made him brothers with Hudhayfa bin Yaman from Ansar. Allah gave him Hudhayfa bin Yaman as the best friend and a heroic brother to him in return for Hudhayfa bin Mughira, who inflicted the heaviest tortures upon him in Makkah. This is the happiest thing. Ammar, who experienced this happiness, thanked Allah all the time.
The person who put forward the idea of masjid for the first time in the history of Islam was Hz. Ammar. When the Messenger of Allah migrated to Madinah, he made an offer by saying, "We need a place of worshipping and resting for the Messenger of Allah." The Mosque of Kuba originated from his idea. Hz. Ammar worked in the construction of this mosque, carrying stones on his shoulders.
Hz. Ammar participated in the battles of Badr and Khandaq. He fought heroically. He fought against the fake Prophet Musaylima. During the battle, he boosted the morale of Muslim mujahids.
One of the Companions that the Prophet loved the most was Ammar. Whenever the Messenger of Allah saw Ammar, his face shone brightly. The following hadiths are significant in that they show how much the Prophet loved Ammar: "He who is hostile to Ammar becomes an enemy of Allah. He who bears a grudge against him and makes him angry will make Allah angry." "Paradise desires Ali, Ammar, Salman and Bilal a lot."
The following incident is a good example showing it:
Once, an argument occurred between Hz. Khalid bin Walid and Hz. Ammar. Hz. Ammar was right. They complained each other to the Messenger of Allah. The Messenger of Allah asked Khalid not to annoy Ammar mentioning the hadiths above about Ammar. Hz. Khalid said, "I swear by Allah, when I left the Messenger of Allah, I could not think of anything other than how to please Ammar."
Ammar, who led a simple and ascetic life, died at the Battle of Siffin in 37 H.
May Allah be pleased with them!
Musnad, 1: 404; Tabaqat, 3: 227; Usdul-Ghaba, 4: 44.
an-Nahl, 106; Ibn Kathir, Tafsirul-Quranil-Azim, 2: 588.