would remain in post-natal bleeding for forty days.” (1)

Majd Ibn Taymiyyah (d. 652 AH) remarked in Al-Muntaqā (1 | 184): “I say: the import of the report is that she was instructed to wait up to forty days, lest the narration be deemed false, for it is impossible that all the women of a single age should share an identical habit in nifās or menstruation.” End quote.

(2) Umm Salamah (may Allah be pleased with her) also said: “A woman from among the Prophet’s wives would remain in post-natal bleeding for forty nights, and the Prophet ﷺ did not order her to make up the prayers missed during that period.” (2)

When the bleeding of a woman in nifās stops before forty days

Benefit:
If the post-natal bleeding ceases before forty days, and the woman performs the ritual bath, resumes prayer and fasting, then the blood returns before the fortieth day, the correct view is that this renewed bleeding is still regarded as nifās; she must cease the acts of worship again, yet any fasts she observed during the intervening period of purity are valid and need not be repeated. See Majmūʿ Fatāwā of Shaykh Muḥammad ibn Ibrāhīm (2 | 102) (3) and the Fatāwā of His Eminence Shaykh ʿAbd al-ʿAzīz ibn Bāz,