Abu Rafi' narrates from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the name of Zaynab (may Allah be pleased with her) was Barrah. It was said to her: "Are you claiming purity for yourself?" Then the Messenger of Allah (peace and blessings be upon him) named her Zaynab.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الضحايا / 19316