الحيي
كلمة (الحيي ّ) في اللغة صفة على وزن (فعيل) وهو من الاستحياء الذي...
Ibn ‘Abbās (may Allah be pleased with him) reported: The Messenger of Allah (may Allah's peace and blessings be upon him) used to prostrate and sleep until his breathing was audible, then he would get up and pray without performing (a new) ablution. I said to him: "You prayed without performing ablution although you had slept." He replied: "Ablution is only necessary for one who slept while lying down."
شرح الحديث :
This Hadīth indicates that ablution is not nullified by light sleep, such as dozing off while firmly seated or while standing. But if someone falls into deep sleep or sleeps while lying down, his ablution is nullified because his joints are relaxed and it is possible that he passes wind in this state.