Khubayb bin Yasaf (r.a.)
The Messenger of Allah (pbuh) was making preparations for the Battle of Badr. When the preparations were completed, the Companions set off to take part in the battle. Meanwhile, somebody ran very fast and caught up with them. He said he wanted to take part in the battle too. Hz. Aisha narrates the incident as follows:
When the Messenger of Allah set off for the Expedition of Badr, somebody caught up with the army at Harratul-Wabra. The courage and heroism of this man, who was tall and well-built, was mentioned a lot. When the Companions saw him, they became very happy. This man went to the Messenger of Allah (pbuh) and said, “I have come to follow you and to fight in your ranks.” The Messenger of Allah (pbuh) asked, “Do you believe in Allah and His Messenger? This man replied, "No." Thereupon, the Messenger of Allah said, Go back. We do not seek the help of the polytheists.”
When the Messenger of Allah reached the place called “Shajara”, the same man came again. He expressed his wish again. The Messenger of Allah gave him the same answer. When the Messenger of Allah reached the place called “Bayda”, he caught up with the Messenger of Allah again. He said he wanted to fight in the same ranks as the Messenger of Allah. The Messenger of Allah asked him again if he believed in Allah and His Messenger. This time he said, “Yes.” Thereupon, the Messenger of Allah said to him, “All right. Come with us.” Thus, he attained the honor of joining the Battle of Badr. 
This person was Khubayb bin Yasaf. This Companion, who had inborn courage and heroism, was a conscientious man who opposed the oppression inflicted upon the Messenger of Allah by the polytheists of Makkah. This hero, who had a spirit that struggled against injustice, could satisfy his great feeling of justice in his spirit only through Islamic principles. His participation in the Battle of Badr was possible only by becoming a Muslim. For, “the Lions of Badr,” were mujahids that were praised in the Quran. Thus, the Messenger of Allah did what the Quranic criterion ordered and invited him to Islam. And Khubayb saw that the light of the truth in his heart united with the light of Islamic belief and joined the caravan of fortunate people.
He fought like a lion in the Battle of Badr. He caused great distress to the Makkan polytheists who wanted to silence the Prophet, who was the purpose of creation and who showed the real way to happiness both in the world and the hereafter and who was given the duty of conveying the message of Islam. He struggled in the best way against the enemies of Islam who struggled in order to deprive humanity of the light of the truth and belief.
During the battle, Hz. Khubayb’s sword was twisted due to the blows. Khubayb went to the Messenger of Allah. The Messenger of Allah fused the sword that had been twisted and cracked with his spit. He straightened it and gave it back to him. 
Khubayb narrates a memory of war as follows:
“When I was in a battle with the Messenger of Allah, one of the polytheists hit my neck. I killed him in return. Afterwards, I married his daughter. My wife would sometimes say to me, “I wish I had not lost the man who gave his daughter to you.” I would answer her as follows: “Instead of saying so, pray so that you will not lose the person who sent your father to the other world quickly.” 
Khubayb attained the honor of joining all of the battles that the Messenger of Allah joined including Badr, Uhud and Khandaq. It is stated that he dealt with not only battles but also inspection. Said bin Musayyab reports that Hz. Umar gave Khubayb the duty of inspecting some affairs. 
He died during the caliphate of Hz. Uthman according to a narration and Hz. Umar according to another narration. It is known that Khubayb bin Yasaf had a grandchild called “Khubayb bin Abdurrahman”, who taught Imam Malik. 
May Allah be pleased with him!
Tabaqat, 3: 535.
al-Isaba, 1: 418.
Usdul-Ghaba, 2: 102.
al-Isaba, 1: 418.
Tabaqat, 3: 535.