Sayyidah Aishah Siddiqah (may Allah be pleased with her) says: A woman's washing of her front private part (after urinating) is (established as) Sunnah.
Imam al-Bazzar recorded this narration; its chain contains a narrator, Layth bin Abi Sulaym, who is a mudallis, and he has narrated this report with "'an'anah" (using the word 'an).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الطهارة / 1062