The Messenger of Allah ﷺ took his oath of separation only because Zaynab returned a gift he had sent her. Ayesha then remarked, "She has humiliated you." This angered him ﷺ, so he swore the oath of separation from his wives.
حدثنا سويد بن سعيد حدثنا يحيى بن زكريا بن أبي زائدة عن حارثة بن محمد عن عمرة
أن رسول الله ﷺ إنما آلى لأن زينب ردت عليه هديته فقالت عائشة لقد أقمأتك فغضب ﷺ فآلى منهن
No references are available.
[Its chain is daif] See hadith no. 56 for its defect.