Abbas bin Abdulmuttalib (r.a.)
Before Islam, service to the Kaaba was regarded as a holy duty. This holy duty was fulfilled by the family of Abbas, one of the noble families of Quraysh. They repaired the Kaaba and gave water to those who visited the Kaaba. Serving the Kaaba was a tradition of this family.
When Abbas was a child, he got lost. His mother looked for him everywhere but she could not find him. She made a vow and said, “If I find Abbas, I will ornament the Kaaba with silk fabric. Then, Abbas appeared. After that, his mother kept her promise. Thus, the Kaaba was covered with silk fabric for the first time in history by the mother of Abbas. Continuing this nice custom of his family, Abbas did not allow anyone to utter bad words in the Kaaba.
Abbas loved his nephew, Muhammad (pbuh), before he became a Muslim, too. He protected Muhammad (pbuh) against Makkan polytheists. The Prophet (pbuh) would consult with him first when he made some important decisions. When Makkan polytheists disturbed the Messenger of Allah (pbuh) a lot, the people of Madinah invited him to their city. Abbas was with the Prophet (pbuh) during the famous Pledge of Aqabah and wanted the people of Madinah to do their best to protect the Messenger of Allah. He addressed the people of Madinah as follows:
"O people of Madinah!You know the position that Muhammad holds among us. We have protected him from his enemies in Makkah and will continue to do so. You invite him to Madinah. Take him there if you can protect him. If you are not sure that you will protect him, give up this attempt."
Thus, Hz. Abbas wanted to guarantee the protection of the Messenger of Allah. When the people of Madinah, Aws and Khazraj tribes, promised that they would protect him like their own lives, the anxiety of Abbas disappeared. Thus, the third Pledge of Aqabah ended with a good result.
During the Battle of Badr, Abbas was in the ranks of the polytheists. The Messenger of Allah gave instructions to all of his Companions not to kill him. He said,
"If you encounter Abbas, do not kill him! Abbas is one of us."
Hz. Abbas was enslaved in the Battle of Badr. The Prophet informed him that he had to pay the ransom like other prisoners of war in order to be saved from slavery. Hz. Abbas said,
"O Messenger of Allah! I am a Muslim. The Quraysh tribe forced me into this war." The Prophet said,
"Allah knows whether you are a Muslim or not. If what you say is true, Allah will give you thawabs. However, you were apparently against us. Try to pay ransom in order to be saved."
After the war, the money Abbas had was seized as booty. Hz. Abbas said to the Prophet,
“At least accept the money you seized from me as my ransom.” The Messenger of Allah (pbuh) did not accept this offer. He said,
“That money is booty that Allah took from you and gave to us.” Hz. Abbas said,
“O Messenger of Allah! I have no other wealth. Will you make me beg money from people in Makkah?” The Prophet (pbuh) said,
“O Abbas! Where are your gold coins?” Hz. Abbas was surprised. He asked the Messenger of Allah,
“What gold?” Thereupon, the Prophet (pbuh) said,
“The gold that you gave to Ummul-Fadl, your wife, on the day you left Makkah! There was nobody else with you then. You said to your wife, 'I do not know what will happen to me during this expedition. If something happens to me and I do not come back, this is for you, this for Fadl, this for Abdullah, this is for Ubaydullah and this is for Qusam.’”
The astonishment of Abbas increased. He said,
"Who told you this? By Allah, there was no one but me and Ummul-Fadl there!" The Prophet said,
"Allah informed me about it." Thereupon, Hz. Abbas said,
“I witness that there is no god but Allah. I also witness that you are the Messenger of Allah.” Thus, he revealed that he was a Muslim. 
The Prophet asked his uncle to return to Makkah, observe the movements of the polytheists and inform him about them. Hz. Abbas returned to Makkah and kept it a secret that he was a believer. He fulfilled very important duties. He conveyed all the details in Makkah to the Messenger of Allah and told him how Makkah could be conquered.
The polytheists knew about this. For this reason, they never loved Hz. Abbas. However, they could not say anything to him. On the other hand, Hz. Abbas felt disturbed when they pulled a face. He sometimes said to the Prophet,
"O Messenger of Allah! I am disturbed by the faces of the polytheists when they pull a face due to seeing me!" The Prophet consoled him by saying,
"They will not enter Paradise unless they love you." He drew attention to the punishment to be inflicted upon them in the hereafter.
Hz. Abbas sometimes thought about migrating and asked permission from the Prophet. However, the Messenger of Allah (pbuh) wanted him to stay in Makkah and said to him,
"Allah will end prophethood with me and migration with you."
The Messenger of Allah (pbuh) loved Hz. Abbas very much. He said the following about him, "He is the most generous one among Qurayshis." He prayed for him as follows: "O Allah! Forgive Abbas and his children, cleanse them from the dirt of sin and protect them!" 
When the Prophet addressed Hz. Abbas, he said, "O uncle of the Messenger of Allah!" Hz. Abbas liked this way of addressing very much. He often came to the Messenger of Allah and asked him to teach him prayer and knowledge. The Messenger of Allah taught him short and concise prayers, and told him to ask for happiness in the world and in the hereafter.
Although Abbas was older than the Messenger of Allah, he showed great respect to him. He did not want to say, "I am older than the Messenger of Allah." When they asked him, "Who is older, you or the Messenger of Allah?", he would say, "He is greater than me, and I am older than him."
Hz. Abbas served Islam a lot after the death of the Prophet too. It was the 18th year of the Migration. A catastrophe of drought and famine affected the entire Arabian Peninsula. All living things were in great trouble due to thirst. The caliph of the Muslims was Hz. Umar. He was desperate in this situation. There was no one to take refuge in except Allah. Hz. Umar took everybody including children and old people with him for the rain prayer. Among them was Hz. Abbas. The caliph of the Muslims Hz. Umar, took Hz. Abbas with him to the pulpit and begged Allah in tears as follows:
"O Lord! When the Messenger of Allah was alive, he would beg you at such times, and you would bestow rain on us. Now, we are begging you with the uncle of the Holy Prophet. Grant us rain."
After this prayer of Hz. Umar’s, Hz. Abbas said:
"O Allah! You are the one who watches and sees everything. You will neither leave a helpless creature alone, nor will you let a camel whose leg is broken die due to hunger. O Lord! Children became very weak. The elderly became skinny. Their cries are heard from the sky. You are the one who knows secret and the most secret things. Help your weak slaves. Show us mercy and help us. They hold me and beg You based on my affinity for Your Messenger. O Lord! Send us rain!"
This appeal reached Allah at once. The clouds became clustered, the sky got dark; thunders were heard. Divine mercy descended on the earth in the form of raindrops. Plants began to yield abundantly. The earth and the creatures became very happy.
May Allah be pleased with the uncle of the Prophet, Hz. Abbas, who died in 32 H at the age of 88!
Tabaqat, 4: 13-14.
Usdul-Ghaba, 3: 310; Tirmidhi, Manaqib: 29.