Sa’d bin Ubada (r.a.)
Sa’d is from the Muslims of Madinah. He took part in the Second Pledge of Aqaba. He worked very hard to enable the light of Islam to enlighten Madinah. He served the cause of Islam with his wealth and life. He took part in all of the battles with the Prophet beginning from the battle of Uhud and carried the standard of the tribe of Aws.
Sa’d had several characteristics shedding light on us. One of his most distinguished characteristics is his generosity. As it is known, man has an inborn love toward worldly possessions. Therefore, it is difficult for the soul to treat food, etc. to others. Therefore, generosity is a characteristic that is loved and liked by people. Hz. Sa’d had a different place among the Companions due to this characteristic. He would treat meals to anybody, whether he knew them or not. He would not sit at the table when there were no guests. He would be pleased when the number of the guests increased. He would send his servant and tell him to invite to the table anybody he wished. 
Sa’d bin Ubada ordered food to the poor ones among the Companions especially to the people of Suffa School. As it is known, the people of Suffa consisted of the Companions who were engaged in learning the Quran and the Sunnah only; they did not do anything else. He tried to meet their needs so that they would learn more things from the Prophet. He sometimes sent food to the place where they lived and sometimes took some of them to his house. Once, he took 80 of those Companions to his house. He treated them various foods.  Sa’d generally bought them clothes too.
The Prophet sometimes went hungry like the other Companions. He even tied a stone around his stomach due to hunger. The Companions knew about this and they wanted to invite the Prophet to their houses. Sa’d usually invited the Prophet to dinner. He sometimes sent food to the Prophet’s house. The Prophet did not reject the invitation and the food of this Companion.
Sa’d felt gratitude toward the Prophet like the other Companions since he caused them to leave polytheism and unbelief and to become Muslims. He was ready to spend everything he had for the sake of the Messenger of Allah. He did not like eating but he liked treating food to the Prophet.
He was on an expedition with the Prophet. A camel of the Prophet that was full of food was lost. The Companions looked for the camel but they could not find it. After a while, the camel returned with the permission of Allah. Hz. Sa’d heard that the camel had been lost but he did not know that it had returned. He spared a little food for himself from the food he had and put the remaining food on a camel and took it to the Prophet. He said, “O Messenger of Allah! I have heard that your camel loaded with food has been lost. I have brought you the food I have. Please accept it.” The Prophet became very pleased with this self-sacrifice of Sa’d and said,
“Allah has sent our camel loaded with food back to us. Take your food with you. May Allah make it blessed for you! O Abu Thabit! Is it not enough what you have done to entertain us since we came to Madinah?”
In return for this statement of the Prophet, Sa’d bin Ubada said, “O Messenger of Allah! We are grateful to Allah and His Messenger because we are honored by Islam. By Allah, what you take from our wealth is more lovable for us than what you leave to us.” Upon this sincere words of Sa’d, the Prophet complemented him:
“O Sa’d! You are right. I give you the glad tiding that you have attained salvation. High ethics is in the hand of Allah. Allah grants high ethics to whomever He wishes. Allah has granted you high ethics.”
Hz. Sa’d, who did not hesitate to give his wealth away in the way of Islam and who spent what God Almighty granted him for His sake, provided weapons, other equipment and food for the mujahids in some battles. Once, he sent dates carried by 10 camels to the army of Islam. The Prophet (pbuh) became very pleased with this self-sacrifice of Sa’d and prayed for him as follows: “O Allah! Protect Sa’d and Sa’d’s family with Your mercy!” Then, he said, “Sa’d bin Ubada is such a good man.”
The Prophet sometimes visited Sa’d as he visited the other Companions. Once, he visited Sa’d. He greeted but he could not get an answer from inside. He greeted again but he did not hear anything. He greeted for the third time. This time he returned when he heard no answer. When Sa’d saw that the Messenger of Allah started to walk away, he ran and said, “O Messenger of Allah! May my mother and father be sacrificed for you! I heard your greeting and answered it with a low voice without making you hear in order to increase your greetings.” Then, he invited the Prophet to his house. He benefitted from his talk for a long time. 
Hz. Sa’d died in 15 H.
May Allah be pleased with him!
Tabaqat, 3: 613.
Hayatus-Sahaba, 2: 317.
Usdul-Ghaba, 2: 283.