Abu Ubayda bin Jarrah (r.a.)
Abu Ubayda bin Jarrah, who was one of the 10 luckiest people who were given the glad tidings of Paradise when they were alive, was one of the first people who accepted Islam. His names was "Amir,"; his nickname was "Abu Ubayda". He was known as "Abu Ubayda bin Jarrah" based on his grandfather. His ancestors and the ancestors of the Messenger of Allah (pbuh) unite in the seventh generation.
Hz. Prophet praised him as follows: "Every ummah has a trustworthy person. The most trustworthy person of this ummah is Abu Ubayda bin Jarrah." . As it is known, one of the nicknames of the Prophet is "al-Amin (the Trustworthy)". With this hadith, the Prophet gave an attribute that belonged to him to Abu Ubayda.
When the people of Yemen asked the Prophet to send them a person to teach them Islam and the Sunnah, the Messenger of Allah sent Abu Ubayda to them.
When he became a Muslim, he had to leave his family at a very young age. His father, who was a polytheist, did not allow him to stay in his house. He tried to practice his religion under very hard circumstances in his house. When migration to Abyssinia became possible, he migrated to Abyssinia in order to get rid of the oppression and torture of the polytheists. Then, he migrated to Madinah and rejoined the Messenger of Allah there. When the Messenger of Allah (pbuh) established the bonds of brotherhood between Ansar and Muhajirs, he made Abu Ubayda brothers with Sa’d bin Muadh of Madinah.
Hz. Abu Ubayda, who was a brave Companion and a heroic mujahid, was together with the Prophet in all battles. He exerted great efforts during the Battle of Badr, which was the most important battle of Islam. He was among the believers and his father was among the polytheists. He was against his father. His father was looking for him and looking for an occasion to kill him. Abu Ubayda moved from place so as not to shed the blood of his father, who was a polytheist. However, it was very difficult and he had to sacrifice his father for his religion. Thereupon, the following verse was sent down: "Thou wilt not find any people who believe in Allah and the Last Day, loving those who resist Allah and His Messenger, even though they were their fathers or their sons, or their brothers, or their kindred." 
During the Battle of Uhud, the polytheists attacked the Prophet, wounded his face and broke one of his teeth. Two links that broke off his helmet pricked his face. When Hz. Abu Ubayda saw the Messenger of Allah like that, he could not bear and removed the links from the Prophet's face through his teeth. Meanwhile, two of his front teeth were broken. 
He joined all of the battles with the Prophet after that. He displayed great sacrifices in all battles.
Abu Ubayda was a person with a very clean heart. When, the Messenger of Allah gave him an order, he would sacrifice his life to fulfill that order. During the Expedition of Salasil, Abu Ubayda did not object to Amr when he asked him to join him with his men and be under his command. He reminded him the following statement of the Messenger of Allah, "Do not conflict with Amr Ibn As." He said to Amr, "Even if you do not obey me, I will obey you."
When Hz. Prophet sent him to Khabat Expedition, he set off with 300 Companions. When their food finished, they had to do with 200 dates for a few days. When they ran out of all food and reached the coast they saw that a big fish had washed up on the shore. They ate it for several days. He returned from the expedition with all of his men safe and sound after fulfilling their duty.
After the death of the Messenger of Allah, the believers regarded Hz. Abu Bakr, Umar and Abu Ubayda appropriate for the caliphate. Hz. Prophet stated the following for Abu Ubayda after Hz. Abu Bakr and Umar: "He is such a good man. …"  Hz. Abu Bakr held Hz. Umar and Abu Ubayda with his hands and offered one of them to be chosen as the caliph. However, they waived their rights and decided to nominate Hz. Abu Bakr as the caliph.
Hz. Abu Ubayda came to the fore among the ummah with his administration, sagacity, wisdom and intelligence. Hz. Umar regarded him as the person that deserved to be the caliph.
When Hz. Abu Bakr became the caliph, he appointed Abu Ubayda to conquer Damascus and the land around. The Islamic Mujahids under the command of Abu Ubayda conquered Homs and Damascus up to Antioch. Besieging Jerusalem after that, Abu Ubayda made the people of Jerusalem accept to sign a contract and to surrender. However, the people of Jerusalem said they would sign the peace contract only if Umar came. Abu Ubayda sent a person to Madinah and invited Umar to Jerusalem. Hz. Umar left Hz. Ali as his deputy and set off. After a long tiring journey that lasted for days, he arrived in Jerusalem. He received the key to Jerusalem.
During the caliphate of Hz.Umar, there was a drought once. Hz. Umar asked help from the governors. The first one to help him was Hz.Abu Ubayda. Hz. Abu Ubayda, who was the governor of Damascus, took 4000 loads of grains to Madinah and distributed them among the Muslims around Madinah.
Hz. Abu Ubayda led a very plain and modest life. His criterion regarding the issue was the following hadith of the Prophet: "The ones that I love among you the best and are closest to me are those who will reach me as I left them." 
During his caliphate, Hz. Umar went to Damascus and the places around it in order to inspect the epidemic of plague. He asked the notables of Damascus who gathered around him, "Where is my brother Abu Ubayda?" they said, "He will arrive soon." After a while, Hz. Abu Ubayda arrived on camelback.
Hz. Umar asked Abu UUbayda to invite him to his house. He wanted to see how his governor lived with his own eyes. they arrived his home. When the Caliph entered his house, he saw a piece of armor and a few things. Thereupon, Hz. Umar asked him, "Do you not have anything else?" He said, "They are enough for my needs." Hz. Umar started to cry and said, "O Abu Ubayda, The world has changed everybody but not you." 
Abu Ubayda (r.a.) was a Companion who was a symbol of virtue in all aspects. He feared Allah a lot and always acted in accordance with the Sunnah of the Messenger of Allah. Fear of Allah was dominant in all of his deeds. He was very modest. He spoke as follows when he was the governor of Damascus:
"I am from Quraysh. However, when I see a person that is superior to me in terms of taqwa whether he has a red or black skin, I say, 'I wish I were in his body'."
Hz. Abu Ubayda was very generous. He would give away whatever he had to the poor. Once Hz. Umar sent him 4000 dirhams through an envoy and said to him, "Pay attention and find out how he will spend the money." When the envoy gave the money to Abu Ubayda, he distributed all of the money to the poor.
Abu Ubayda (r.a.), who was adherent to his duty wholeheartedly and who was very enthusiastic with the love of the Messenger of Allah, looked after the people who were under his command as if they were his own children. His mercy and compassion encompassed not only Muslims but also Christians. Therefore, Christians served him and gave him information about the movements of the enemy by watching them.
Abu Ubayda bin Jarrah, died of plague at the age of 58 in the 18th year of the Migration.
May Allah be pleased with him!
 Tirmidhi, Manaqib: 33.
 al-Mujadala, 22.
 Usdul-Ghaba, 3: 85.
 Tirmidhi, Manaqib: 33.
 Asr-ı Saadet, 2: 66.
 Musnad, 1: 196.
 Isaba, 2: 254; Usdul-Ghaba, 3: 85.