The Book of the Merits of the Companions
حَدَّثَنَا عَبْدُ بْنُ حُمَيْدٍ، أَخْبَرَنَا عَبْدُ الرَّزَّاقِ، أَخْبَرَنَا مَعْمَرٌ، عَنِ الزُّهْرِيِّ، عَنْ عُرْوَةَ، عَنْ عَائِشَةَ، قَالَتْ مَا غِرْتُ لِلنَّبِيِّ صلى الله عليه وسلم عَلَى امْرَأَةٍ مِنْ نِسَائِهِ مَا غِرْتُ عَلَى خَدِيجَةَ لِكَثْرَةِ ذِكْرِهِ إِيَّاهَا وَمَا رَأَيْتُهَا قَطُّ .A'isha reported:Never did I feel jealous of any wife amongst the wives of Allah's Apostle (ﷺ) as I feel in case of Khadija (though I had never seen her), for he praised her very often
From Sahih Muslim, whose reports the scholars accept as authentic.