The explanation of this Hadith is that if the reference is to the duration of her menstruation during nifas, then there is no uniform limit applicable to all women. This is because the habits of women vary; some menstruate for fewer days, while others menstruate for the maximum duration. This does not contradict the narrations we have presented earlier. The Shaykh (Al-Mufid), may Allah سبحانه وتعالى support him, further stated: "It is disliked (makruh) for a menstruating woman or a woman in nifas to dye their hands or feet with henna or similar substances that water cannot easily remove, as this may prevent water from reaching the surface of the limbs during purification. It is also disliked for a person in a state of janaba to apply dye after entering the state of janaba but before performing ghusl. However, if someone applies dye before becoming junub and then enters janaba, there is no harm in this. Similarly, if a woman applies dye after menstruation and bleeding subsequently resumes while the dye is still present, there is no issue. However, initiating the application of dye during menstruation or janaba carries a different ruling, as previously explained."
Commentary #33