He saw the Prophet ﷺ fall asleep while in prostration until he snored or breathed heavily, then he got up and prayed.I said, "Messenger of Allah, you fell asleep."He replied, "Ablution is only required upon one who sleeps lying down, for when a person lies down, his joints become relaxed."
حدثنا إسمعيل بن موسى كوفي وهناد ومحمد بن عبيد المحاربي المعنى واحد قالوا حدثنا عبد السلام بن حرب الملائي عن أبي خالد الدالاني عن قتادة عن أبي العالية
أنه رأى النبي ﷺ نام وهو ساجد حتى غط أو نفخ ثم قام يصلي فقلت يا رسول الله إنك قد نمت قال إن الوضوء لا يجب إلا على من نام مضطجعا فإنه إذا اضطجع استرخت مفاصله
Its chain of transmission is daif. Abu Dawud narrated it in Kitab al-Tahara, Bab fil-Wudu min al-Nawm, hadith no. 202, from Hannad, with the same wording, and said, "It is a munkar hadith." Daraqutni declared it daif in 1/159, 160, as did others.Abu Khalid and his teacher are both mudallis narrators, and they narrated it with an ambiguous form of transmission (an'ana).On this subject there are also narrations from Ayesha [Ibn Majah, hadith no. 474], Ibn Masud [Ibn Majah, hadith no. 475], and Abu Hurairah [Bayhaqi 1/119, as a stopped narration, though he indicated it could be traced back to the Prophet, see also Nasb Raya 1/46].