Anas ibn Malik reported: The Prophet, peace be upon him, entered the mosque and saw a rope between two pillars. He asked, “What is this rope?” They said, “This rope is for Zainab who uses it when she becomes tired during prayer.” The Prophet said, “Do not use it. You should pray when you have energy, but if you feel tired you should sit down.”
[Sahih Bukhari, Book 21, Number 251]
عَنْ أَنَسِ بْنِ مَالِكٍ رَضِيَ اللَّهُ عَنْهُ قَالَ
دَخَلَ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فَإِذَا حَبْلٌ
مَمْدُودٌ بَيْنَ السَّارِيَتَيْنِ فَقَالَ مَا هَذَا الْحَبْلُ قَالُوا هَذَا حَبْلٌ لِزَيْنَبَ فَإِذَا فَتَرَتْ تَعَلَّقَتْ فَقَالَ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ لَا حُلُّوهُ لِيُصَلِّ أَحَدُكُمْ نَشَاطَهُ فَإِذَا فَتَرَ فَلْيَقْعُدْ
صحيح البخاري كتاب التَّهَجُّد بَاب مَا يُكْرَهُ مِنْ التَّشْدِيدِ فِي الْعِبَادَةِ
