Hazrat Abu Huraira (may Allah be pleased with him) narrated that the name of Umm al-Mu'mineen Zainab (may Allah be pleased with her) was "Barrah." It began to be said that she declares her own purity. Therefore, the Prophet (peace and blessings of Allah be upon him) named her Zainab.
Hadith Referenceاللؤلؤ والمرجان / كتاب الآداب / 1384
Hadith Gradingمحدثین:«صحیح»
Hadith Takhrij«صحیح، أخرجه البخاري في: 78 كتاب الأدب: 108 باب تحويل الاسم إلى اسم أحسن منه»
Brief Explanation
The word "Barrah" means very pious. This was not liked by the Messenger of Allah (sallallahu alayhi wa sallam), because it carries a hint of self-righteousness. Therefore, this name was changed. (Raaz)