[Machine] The shortest time of menstruation is one day.  

أَدْنَى وَقْتِ الْحَيْضِ يَوْمٌ  

[Machine] I heard Al-Awza'i say, "Here, we have a woman who menstruates during the day and becomes pure at night."  

سَمِعْتُ الْأَوْزَاعِيَّ يَقُولُ عِنْدَنَا هَاهُنَا امْرَأَةٌ تَحِيضُ غُدْوَةً وَتَطْهُرُ عَشِيَّةً  

[Machine] "It has always been the case that she menstruates for one day and does not exceed it, and it has been confirmed to me about women that they have always menstruated for less than three days, and about women that they have always menstruated for fifteen days, and about a woman that she has always menstruated for thirteen days. How did I claim that what we know to be true is not true? The Sheikh said that it has been narrated to us from Ali and Shuraikh that they permitted three menstrual cycles in a month and five nights. This is mentioned in the book of Al-Adad, God willing. Al-Shafi'i said, and we say, based on what has been narrated from Ali, because it is in line with what has been narrated from the Prophet ﷺ that there is no fixed time for menstruation, and he relied on the hadith of the Prophet ﷺ that when the menstrual blood comes, leave the prayer, and when its duration is over, wash the blood off and pray."  

أَنَّهَا لَمْ تَزَلْ تَحِيضُ يَوْمًا وَلَا تَزِيدُ عَلَيْهِ وَأُثْبِتَ لِي عَنْ نِسَاءٍ أَنَّهُنَّ لَمْ يَزَلْنَ يَحِضْنَ أَقَلَّ مِنْ ثَلَاثٍ وَعَنْ نِسَاءٍ أَنَّهُنَّ لَمْ يَزَلْنَ يَحِضْنَ خَمْسَةَ عَشَرَ وَعَنِ امْرَأَةٍ أَكْثَرَ أَنَّهَا لَمْ تَزَلْ تَحِيضُ ثَلَاثَ عَشْرَةَ وَكَيْفَ زَعَمْتُ أَنَّهُ لَا يَكُونُ مَا عَلِمْنَا أَنَّهُ يَكُونُ قَالَ الشَّيْخُ وَرُوِّينَا عَنْ عَلِيٍّ وَشُرَيْحٍ أَنَّهُمَا جَوَّزَا ثَلَاثَ حِيَضٍ فِي شَهْرٍ وَخَمْسِ لَيَالٍ وَذَلِكَ يَرِدُ فِي كِتَابِ الْعِدَدِ إِنْ شَاءَ اللهُ تَعَالَى قَالَ الشَّافِعِيُّ وَنَحْنُ نَقُولُ بِمَا رُوِيَ عَنْ عَلِيٍّ ؓ لِأَنَّهُ مُوَافِقٌ لِمَا رُوِيَ عَنِ النَّبِيِّ ﷺ أَنَّهُ لَمْ يَجْعَلْ لِلْحَيْضِ وَقْتًا وَاحْتَجَّ بِحَدِيثِ النَّبِيِّ ﷺ إِذَا أَقْبَلَتِ الْحَيْضَةُ فَاتْرُكِي الصَّلَاةَ وَإِذَا ذَهَبَ قَدْرُهَا فَاغْسِلِي الدَّمَ عَنْكِ وَصَلِّي  

Fatima bint Abi Hubaish said to Messenger of Allah ﷺ, "O Messenger of Allah ﷺ! I do not become clean (from bleeding). Shall I give up my prayers?" Messenger of Allah ﷺ replied: "No, because it is from a blood vessel and not the menses. So when the real menses begins give up your prayers and when it (the period) has finished wash the blood off your body (take a bath) and offer your prayers." (Using translation from Bukhārī 306)   

أَنَّهَا قَالَتْ قَالَتْ فَاطِمَةُ بِنْتُ أَبِي حُبَيْشٍ لِرَسُولِ اللهِ ﷺ يَا رَسُولَ اللهِ إِنِّي لَا أَطْهُرُ أَفَأَدَعُ الصَّلَاةَ؟ فَقَالَ رَسُولُ اللهِ ﷺ إِنَّمَا ذَلِكَ عِرْقٌ وَلَيْسَ بِالْحَيْضَةِ فَإِذَا أَقْبَلَتِ الْحَيْضَةُ فَاتْرُكِي الصَّلَاةَ فَإِذَا ذَهَبَ قَدْرُهَا فَاغْسِلِي الدَّمَ عَنْكِ وَصَلِّي