Musannaf Ibn Abi Shayba 3:897

Abu al-Ahwas narrated to us, from Abu Ishaq, from Sa'id ibn Wahb, from Khabbab, who said: We complained to the Messenger of Allah (may Allah bless him and grant him peace) about [performing] prayer in the intense heat, but he did not complain [i.e., he did not excuse us or grant us our request].