Sahih Muslim , Book 31, Hadith 5972 (USC-MSA) ⓘ
'A'isha reported: Never did I feel jealous of the wives of Allah's Apostle but in case of Khadija, although I did no, (have the privilege to) see her. She further added that whenever Allah's Messenger slaughtered a sheep, he said: Send it to the companions of Khadija I annoyed him one day and said: (It is) Khadija only who always prevails upon your mind. Thereupon Allah's Messenger said: Her love had been nurtured in my heart by Allah Himself.
حَدَّثَنَا سَهْلُ بْنُ عُثْمَانَ، حَدَّثَنَا حَفْصُ بْنُ غِيَاثٍ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنْ أَبِيهِ، عَنْ عَائِشَةَ، قَالَتْ مَا غِرْتُ عَلَى نِسَاءِ النَّبِيِّ صلى الله عليه وسلم إِلاَّ عَلَى خَدِيجَةَ وَإِنِّي لَمْ أُدْرِكْهَا . قَالَتْ وَكَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم إِذَا ذَبَحَ الشَّاةَ فَيَقُولُ " أَرْسِلُوا بِهَا إِلَى أَصْدِقَاءِ خَدِيجَةَ " . قَالَتْ فَأَغْضَبْتُهُ يَوْمًا فَقُلْتُ خَدِيجَةَ فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " إِنِّي قَدْ رُزِقْتُ حُبَّهَا " .
also referenced under: Book 44, Hadith 108 (In-Book) & Hadith 2435 (Reference)