Musannaf Ibn Abi Shaybah

Hazrat Anas (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) once came and saw a rope tied. He asked, "What is this?" He was told, "O Messenger of Allah! Such-and-such woman prays, and when she gets tired, she leans on this rope for support." The Prophet (peace and blessings be upon him) said, "One should pray as long as one is energetic, and when one gets tired, one should sleep."

A female servant of Hazrat Abu Hazim says that I was among the people of Suffa. We had ropes; when we became tired in prayer or felt sleepy, we would hold onto those ropes, and we also had mats on which we would stand to protect ourselves from the hardness of the ground. Once, Hazrat Abu Bakr came and said, "Cut these ropes and pray on the ground."

Hazrat Hudhaifah (may Allah be pleased with him) said that this is how the Jews used to do. That is, to tie themselves from below in this manner.