Narrated Anas bin Malik:
The Verse: 'But you did hide in your mind that which Allah was about to make manifest.' (33.37) was revealed concerning Zainab bint Jahsh and Zaid bin Haritha. (ES)
USC-MSA web (English) reference: Vol. 6, Book 60, Hadith 310 (ES)
Arabic reference (ES): Book 65, Hadith 4787 (ES)