Sayyiduna Abdullah bin Umar (may Allah be pleased with them) narrated that Sayyiduna Umar (may Allah be pleased with him) said to the Prophet (peace and blessings of Allah be upon him) that he sometimes needed to perform ghusl (ritual bath) at night. So the Messenger of Allah (peace and blessings of Allah be upon him) said to him: Perform ablution, wash your private parts, and then go to sleep.
Hadith Referenceاللؤلؤ والمرجان / كتاب الحيض / 178
Hadith Gradingمحدثین:«صحیح»
Hadith Takhrij«صحیح، أخرجه البخاري في: 5 كتاب الغسل: 27 باب الجنب يتوضأ ثم ينام»