What is the evidence for the maximum length of menses being fifteen days, and what is the maximum length of tuhr (purity)?

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Check below answers in case you are looking for other related questions:
How can a woman determine that her period has ended so that she can pray?
If the bleeding lasts for more than 15 days is it still regarded as menstruation, and can she fast?

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Related Answers:
She did ghusl and prayed without washing her hair
She thought that the bleeding that results from an abortion was nifaas so she broke her fast
She continued to bleed after she gave birth so she did not pray; should she make up the days that she missed after forty days from the birth?
How can a woman determine that her period has ended so that she can pray?
If the bleeding lasts for more than 15 days is it still regarded as menstruation, and can she fast?

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