Lady Khadijah occupied the feelings and emotions of the Prophet (a.s.) and had a very high position near him. He loved her too much and was loyal to her.
Aa’ishah, the Prophet’s wife, said, ‘The Prophet, when going out of home, often mentioned Khadijah (after her death) and praised her. Once, he mentioned her, but I became jealous and said, ‘She was but an old woman that Allah has given you in place of her better than her.’
The Prophet (a.s.) became angry until his forelock shook because of anger, and then he said, ‘No, by Allah, Allah has not given me in place of her better than her. She believed in me when people disbelieved, comforted me with her money when people denied me, and Allah had granted me offspring from her where He had not granted me from other wives.’
Once, Halah, Khadijah’s sister, came to Medina and visited the Prophet’s house. When the Prophet (a.s.) heard her voice, which was like the voice of Khadijah, in the yard of the house, he said, ‘O my Lord, she is Halah bint Khuwaylid…’
Aa’isha could not control herself and she said, ‘What do you remember from an old woman from the old women of Quraysh?... She died since long, and Allah has given you in place of her better than her.’
When the Prophet (a.s.) slaughtered a sheep, he said (to servants), ‘Take (some meat) to the friends of Khadijah!’
Once, Aa'isha said to him, ‘Why do you do that?’
He said, ‘I do like her beloveds.’
In another tradition, it was narrated that the Prophet (a.s.) had said, ‘I have been granted her love.’
Envy overcame Aa'isha when she often heard the Prophet (a.s.) praising Khadijah. She said, ‘I did never envy a woman like I did to Khadijah. The messenger of Allah (a.s.) did not marry me except after her death.’
The soul of Khadijah was with the Prophet (a.s.) whenever he went. His soul was full of her love. He often and always remembered her and prayed Allah to have mercy on her.
The gifts of Allah on her
Allah the Almighty had endowed Khadijah with gifts that no any other one of the Prophet’s wives had been endowed with. From the great gifts of Allah to her was that Allah had made her the mother of the best woman Allah had ever created in the earth since the beginning of the creation until the Day of Resurrection; Fatima (a.s.) the principal of the women of the worlds, and made her the grandmother of the two grandson of the Prophet (a.s.), two infallible imams, and two masters of the youth of Paradise; Imam al-Hasan and Imam al-Husayn (peace be on them), and the grandmother of Lady Zaynab, the first wronged and oppressed woman in Islam. Allah had made Khadijah the grandmother of the infallible imams who were his authorities on His people. These heavenly gifts that Khadijah had been endowed with had not been given to any woman other than her at all.
source : http://www.maaref-foundation.com
