Sahih Bukhari
Merits of the Helpers in Madinah (Ansaar)
Volume: 005 / Book Number: 058 / Hadith Number: 165
Narrated 'Aisha:
I did not feel jealous of any woman as much as I did of Khadija because Allah's Apostle used to mention her very often. He married me after three years of her death, and his Lord (or Gabriel) ordered him to give her the good news of having a palace of Qasab in Paradise.