Musannaf Ibn Abi Shayba 6:530

Hafs ibn Ghiyath narrated to us, from Hajjaj, from al-Walid ibn Abi Malik, from Sa’id ibn al-Musayyib, and from Ash’ath, from al-Hasan and Ibn Sirin; they said: If the funeral [prayer] and the obligatory prayer are both present, one begins with the obligatory prayer.