Asma bint Yazid reported,
She was divorced during the time of the Messenger of Allah ﷺ, and at that time there was no waiting period prescribed for a divorced woman. So when Asma was divorced, Allah 
revealed the ruling concerning the waiting period for divorce. She was thus the first woman concerning whom the waiting period for divorced women was revealed.
Abu Dawud 2281
Hasanحدثنا سليمان بن عبد الحميد البهراني حدثنا يحيى بن صالح حدثنا إسمعيل بن عياش حدثني عمرو بن مهاجر عن أبيه
عن أسماء بنت يزيد بن السكن الأنصارية
أنها طلقت على عهد رسول الله ﷺ ولم يكن للمطلقة عدة فأنزل الله عز وجل حين طلقت أسماء بالعدة للطلاق فكانت أول من أنزلت فيها العدة للمطلقات
No references are available.
[Its isnad is hasan] Ibn Abu Hatim narrated it in his Tafsir, 2/414, no. 2186, from the hadith of Ismail bin Ayyash through him, and Bayhaqi narrated it, 7/424, from the hadith of Abu Dawud through him.