Diseases attacked the Mother of Believers Khadijah and death approached her soon. In the last moments of her life, she felt pain whenever she looked at her only daughter Fatima az-Zahra’ (a.s.) who was a young child then. She looked at Fatima (a.s) with pain and sigh. She recommended the Prophet (a.s.) to take much care of her.
It was not long until Khadijah left to the better world and her pure soul rose towards its Creator surrounded by angels and received by the prophets with takbir and tahlil.
The Prophet (a.s.) was afflicted by the great loss of Khadijah who filled his life with satisfaction and tranquility, and relieved him from the persecution of the oppressors of Quraysh. He was very sad when she died.
Anyhow, he washed, enshrouded, and offered the prayer on her. He dug a grave for her and buried her in it. The loss of Khadijah caused the Prophet (a.s.) a great sorrow until he called that year where also his uncle Abu Talib died in it “the year of sorrow”.
Death took Khadijah, who was the most loyal to the Prophet (a.s.), the most loving, and the best supporter to him and to his mission.
Khadijah left her daughter Fatima (a.s), who was a young child yet, overcome by grief and sorrow. Fatima (a.s) lost her kind, loving mother since her early years, and then she took the role of her mother toward her father (a.s.) who still faced the harms and aggressions of Quraysh. Fatima (a.s) comforted the loneliness of her father after her mother, relieved his sufferings, and served him with her love and kindness until she was called “the mother of her father”.
source : http://www.maaref-foundation.com