رُخِّصَ لِلْحَائِضِ أَنْ تَنْفِرَ إِذَا حَاضَتْ. وَكَانَ ابْنُ عُمَرَ يَقُولُ فِي أَوَّلِ أَمْرِهِ إِنَّهَا لاَ تَنْفِرُ. ثُمَّ سَمِعْتُهُ يَقُولُ تَنْفِرُ إِنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم رَخَّصَ لَهُنَّ.
Ibn Abbas reported: The menstruating woman was permitted to depart if she gets her menses. And Ibn Umar used to say at first, “She does not depart.” Then I heard him say, “She departs; the Messenger of Allah ﷺ permitted them (to do so).”
also in Sahih al-Bukhari 330