ENOfficial
It was narrated from Abu Hurairah that: "Zainab used to be called "Barrah" (good), and it was said that she was praising herself. So the Messenger of Allah(ﷺ) changed her name to Zainab."
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا أَبُو بَكْرٍ، حَدَّثَنَا غُنْدَرٌ، عَنْ شُعْبَةَ، عَنْ عَطَاءِ بْنِ أَبِي مَيْمُونَةَ، قَالَ سَمِعْتُ أَبَا رَافِعٍ، يُحَدِّثُ عَنْ أَبِي هُرَيْرَةَ، أَنَّ زَيْنَبَ، كَانَ اسْمُهَا بَرَّةَ فَقِيلَ لَهَا تُزَكِّي نَفْسَهَا فَسَمَّاهَا رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ زَيْنَبَ .
sunnah.com