Musannaf Ibn Abi Shayba 18:1047

Abu Bakr narrated to us, he said: Hafs narrated to us, from ‘Amr, from al-Hasan, he said: If a young boy and a slave gather to commit a killing, then it is [the payment of] one blood money. And if they gather, and this one strikes with a sword and that one strikes with a staff, then it is [the payment of] one blood money.