Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) came to the house of Sayyiduna Abu Musa al-Ash'ari (may Allah be pleased with him), and meanwhile the time of prayer came. Sayyiduna Abu Musa (may Allah be pleased with him) said to him: Step forward, O Abu Abd al-Rahman, for you are older in age and more knowledgeable. He said: No, rather you step forward, for we have come to you in your house and your mosque. So Abu Musa (may Allah be pleased with him) stepped forward and took off his sandals. When he had finished the prayer, Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) said: "What did you intend by taking them off? Are you in the sacred valley of Tuwa? I have seen the Messenger of Allah (peace and blessings be upon him) pray in leather socks and sandals."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 9230