Q: I would like to know if it is mentioned in the Hadith regarding a woman who has given birth whether she has to stay indoors for 40 days and also how long after giving birth can a woman begin reading salaah and fasting?
A: It is not mentioned in Hadeeth.
The maximum for Nifaas is forty days and there is no minimum. When the Nifaas stops (on whichever day), she will take a bath and begin Salaah.
If the blood exceeds 40 days (in the case of the first baby), she will take a bath when the forty days end and begin Salaah.
It is a misconception that Salaah can only be started after forty days, although the blood stopped before that. When the blood stops, even if it is on the 5th, 10th or 15th day, Salaah immediately becomes compulsory.
Moulana Yusuf Laher