Musannaf Ibn Abi Shayba 13:2173

Abu Bakr narrated to us, he said: Abbad ibn al-Awwam narrated to us, from Umar ibn Amir, from Qatadah, from Sa’id ibn al-Musayyib, and from Hammad, from Ibrahim; they both said: There is no harm in selling grape juice (must) as long as it has not boiled.