Musannaf Ibn Abi Shayba 7:9

Abu Bakr ibn Ayyash narrated to us, from Abu Husayn, from Sa’id ibn Jubayr, who said: A man came to Ibn Abbas and said, "I vowed to stand on [Mount] Qu’ayqi’an naked until nightfall." Ibn Abbas said, "The devil wanted to expose your private parts and for the people to laugh at you. Wear your clothes and pray two rak'ahs at the Hijr."