One who stands up at night: Is istinja' (cleaning oneself after relieving oneself) obligatory for him, and if he performs wudu' (ablution) without istinja', is his prayer valid?

Question:
Honorable Shaykh, may Allah grant you success. A man slept through the night and then got up. Is istinja' obligatory for him? And if he prays after performing wudu' without istinja', is his prayer valid?

Answer:
Sleep does not make istinja' obligatory. What makes istinja' obligatory is the passing of waste. If something passes from him, he must perform istinja' or istijmar (cleaning with stones). As for mere sleep, it does not make istinja' obligatory.