Asma' daughter of Abu Bakr said: I heard a woman asking the Messenger of Allah (ﷺ): What should any of us to with her clothe (in which she menstruated) when she becomes purified ? Can she pray in that (clothe) ? He said: She should see; if she finds blood in it, she should scratch it with some water and (in case of doubt) sprinkle upon it (some water) and pray so long as she does not find (any blood).
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا عَبْدُ اللَّهِ بْنُ مُحَمَّدٍ النُّفَيْلِيُّ، حَدَّثَنَا مُحَمَّدُ بْنُ سَلَمَةَ، عَنْ مُحَمَّدِ بْنِ إِسْحَاقَ، عَنْ فَاطِمَةَ بِنْتِ الْمُنْذِرِ، عَنْ أَسْمَاءَ بِنْتِ أَبِي بَكْرٍ، قَالَتْ سَمِعْتُ امْرَأَةً، تَسْأَلُ رَسُولَ اللَّهِ صلى الله عليه وسلم كَيْفَ تَصْنَعُ إِحْدَانَا بِثَوْبِهَا إِذَا رَأَتِ الطُّهْرَ أَتُصَلِّي فِيهِ قَالَ " تَنْظُرُ فَإِنْ رَأَتْ فِيهِ دَمًا فَلْتَقْرُصْهُ بِشَىْءٍ مِنْ مَاءٍ وَلْتَنْضَحْ مَا لَمْ تَرَ وَلْتُصَلِّ فِيهِ " .
sunnah.com