Musnad Abu Ya'la al-Mawsili 150:152

'Abd al-A'la narrated to us, 'Abd Allah ibn Dawud narrated to us, from Hisham ibn 'Urwah, from his father, from 'Aishah—if Allah wills—that the Prophet (peace and blessings of Allah be upon him) said: "Delay the Dhuhr prayer during the heat." Abu Ya'la said: "This is how 'Abd al-A'la narrated it to us, with doubt."