Sayyiduna Anas bin Malik (may Allah be pleased with him) says: The menstruating woman should wait five, seven, eight, nine or ten days; when the ten days have passed, she is counted as a woman with istihadah (irregular bleeding).
Imam Abu Ya'la recorded it; its chain contains a narrator, al-Jald bin Ayyub, who is da'if (weak).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الطهارة / 1537