Musnad Ahmad 7:32

Yahya ibn Adam narrated to us, Ibn Abi Dhi'b narrated to us, Muslim ibn Jundub narrated to us, he who heard Az-Zubayr ibn al-Awwam say narrated to me: "We used to pray Jumu'ah with the Messenger of Allah, may Allah bless him and grant him peace, then we would hasten, and we would not find any shade except for the place of our feet—or he said: We would not find any shade for the place of our feet."