There have been many women in the history of the world who have become great and famous because of their great deeds. Mankind can justly be proud of them.
But in the entire history of the world, there are only four women who could measure up to the high standards of true greatness and perfection set by Islam. They measured up to these standards by dint of their great services to Allah. Muhammed Mustafa, the Prophet of Islam, the Recipient of Revelation from Heaven, and its Interpreter, identified them. They are:

1. Asiya, the wife of Pharaoh
2. Maryam (Mary), the mother of Isa (Jesus)
3. Khadija, the daughter of Khuwayled, and
4. Fatima Zahra, the daughter of Muhammed Mustafa (S)

Muhammed Mustafa found only four perfect women in the entire human race. Out of these four, the last two belong to the same house; they are Khadija, the mother, and Fatima, her daughter.
Khadija was the image of the perfect soul.
In the rest of mankind, the only other women who might qualify as perfect, would be the other wives of Muhammed Mustafa. But he himself gave the verdict in this matter, and his verdict remains irrevocable. He mentioned only Khadija out of all his wives as the perfect woman, and thus excluded - by a fiat his other wives from the group of perfect women.
Khadija combined in her person all those attributes which add up to perfection. If she had lacked any of those attributes, her husband would not have classified her as perfect. And there is no evidence that she had any of those frailties which are said to be characteristic of womanhood as a rule.
One of the characteristic weaknesses of women is said to be jealousy. Khadija was untouched by jealousy of any kind. She was a woman who found fulfillment, pleasure and satisfaction in giving. She was a munificent patron of the poor. She was at her very best when she was feeding the hungry and comforting the cheerless. The acts of feeding and comforting the hungry and the cheerless did not call for a conscious effort on her part; for her they had become a reflex.
Just as Khadija was free from jealousy, she was also free from cynicism. One thing she never did, was to hurt anyone. She never made fun of any woman; she never tried to belittle anyone; she never despised anyone; she was never angry and never spiteful; and she was strictly nonjudgmental. She never uttered an ugly or a pejorative word against anyone. So true to the dimensions of the understanding heart, she was solicitous of the feelings of even the humblest and the poorest of women, and she was distressed by the distress of other people.

There was a time when Khadija was called the Princess of the Merchants and the Princess of Makka. Then a time came when her great fortune changed hands. From her hands, it passed into the hands of Islam. She was rich and she became poor in the material sense. She exchanged a lifestyle of luxury for a lifestyle of austerity. But nothing changed in her temperament. She remained cheerful, magnanimous, and idealistic as before. She spent more time than ever in devotions to Allah, and in service to His messenger, and of course, she was never forgetful of the well-being and welfare of the Community of the Faithful.
The following verse in Quran Majid may be referring to her:

... AND THERE ARE SOME WHO ARE, BY GOD'S LEAVE, FOREMOST IN GOOD DEEDS; THAT IS THE HIGHEST GRACE.
(Chapter 35; verse 32)

Khadija, the idealist, was foremost in doing "good deeds." She had an air of compelling sanctity about her. Through her "good deeds" she became the recipient of the "highest graces" from Heaven.
Khadija was the ideal woman, the ideal wife for Muhammed Mustafa, the ideal mother for her children, and the ideal Mother of the Believers.
Faith in Allah's mercy was the spring from which Khadija took her life's responses. She was endowed with what Quran Majid has called Qalb Saleem (nthe sound heartn) in verse 89 of its 26th chapter. Qalb Saleem or the sound heart, has been defined by A. Yusuf Ali, the translator and commentator of Quran Majid, as follows:
"A heart that is pure, and unaffected by the diseases that afflict others. As the heart in Arabic is taken to be not only the seat of feelings and affections, but also of intelligence and resulting action, it implies the whole character."
Khadija's symmetry of character was an index of her Qalb Saleem.