(a) Sa'id bin al-As said that it is narrated from Sayyiduna Uthman and Sayyidah Aishah (may Allah be pleased with them both) that Sayyiduna Abu Bakr (may Allah be pleased with him) asked permission to come to the Messenger of Allah (peace and blessings be upon him) while he (peace and blessings be upon him) was lying on the bed wrapped in the wrap of Sayyidah Aishah (may Allah be pleased with her). Sayyiduna Abu Bakr (may Allah be pleased with him) was given permission to come in, and he (peace and blessings be upon him) remained in that state. He stated his need and left. Then Sayyiduna Umar (may Allah be pleased with him) asked permission; he too was given permission while the Messenger of Allah (peace and blessings be upon him) remained in that state, and he too stated his need and left. Sayyiduna Uthman (may Allah be pleased with him) said: Then I asked permission of the Messenger of Allah (peace and blessings be upon him), and the Messenger of Allah (peace and blessings be upon him) sat up and said to Sayyidah Aishah (may Allah be pleased with her): "Gather your clothes about you." Sayyiduna Uthman (may Allah be pleased with him) said: I put my need before him and then I too left. Sayyidah Aishah (may Allah be pleased with her) said: O Messenger of Allah! I did not see you hasten to sit up when Abu Bakr and Umar (may Allah be pleased with them both) came, the way you hastened to sit up when Uthman (may Allah be pleased with him) came? The Messenger of Allah (peace and blessings be upon him) said: "Uthman (may Allah be pleased with him) is a very modest man. I feared that if I gave him permission while I was in that state, he might not be able to state his need."
(b) In the narration of Sahih Muslim, neither the thigh nor the shin is mentioned.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3243