Sayyiduna Anas bin Malik (may Allah be pleased with him) said that the Prophet (peace and blessings be upon him) entered the mosque and saw a rope tied between two pillars. He (peace and blessings be upon him) asked: "What is this?" They said: "This belongs to Zaynab (may Allah be pleased with her); she prays with its support when she becomes tired." The Prophet (peace and blessings be upon him) said: "Untie it. Let each of you pray while energetic, and when he becomes tired, let him sit down."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4739