From Sahih Muslim (Hadith 6277):
A'isha reported:Never did I feel jealous of any woman as I was jealous of Khadija. She had died three years before he (the Holy Prophet) married me. I often heard him praise her, and his lord, the Exalted and Glorious, had commanded him to give her the glad tidings of a palace of jewels in Paradise: and whenever he slaughtered a sheep he presented (its meat) to her female companions
Reference: Muslim 6277