Nifās has no minimum length: the moment the bleeding genuinely stops — whether after ten days or twenty — she performs ghusl and resumes prayer and fasting, and she becomes lawful to her husband. Its maximum, according to the majority (Ḥanafīs, Shāfiʿīs and Ḥanbalīs), is forty days: Umm Salamah رضي الله عنها reported that the women in nifās in the time of the Prophet ﷺ would refrain from prayer for forty days or forty nights (Sunan Abi Dawud 311; Jamiʿ at-Tirmidhi 139). Al-Tirmidhī records immediately after it that the people of knowledge among the Companions, the Tābiʿīn and those after them agreed that the woman in nifās leaves the prayer for forty days unless she sees purity before that, in which case she makes ghusl and prays. (The Mālikīs put the maximum at sixty days.) If bleeding continues beyond forty days and does not coincide with her habitual menstrual period, it is treated as istiḥāḍah: she makes ghusl, prays normally, and simply renews wuḍūʾ for each prayer time. Like the menstruating woman, she makes up the fasts she missed but not the prayers, as ʿĀʾishah رضي الله عنها said: "We used to menstruate in the time of the Messenger of Allah ﷺ, and we were ordered to make up the fasts but were not ordered to make up the prayers" (Jamiʿ at-Tirmidhi 787).
Q&A · Women in Islam
How long is nifās (bleeding after childbirth), and when does a woman resume praying?
Evidence — the daleel
On deen2u
Informational, not a personal fatwa. Consult a qualified scholar for rulings on your situation.