It is narrated from Humayd bin Nafi' al-Ansari (may Allah have mercy on him) that he narrated a hadith with the same meaning and added something to it. Humayd said: I asked Sayyidah Zaynab (may Allah be pleased with her): What is 'the head of the year'? Sayyidah Zaynab (may Allah be pleased with her) said: In the Days of Ignorance, when a woman's husband died, she would go to the worst house she had and sit in it, until, when a year had passed over her, she would come out and throw a piece of dung, that is, rub it against her body and throw it away; and Allah knows best.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب العدد / 15466