Musnad Ahmad 27:1164

Muhammad ibn Bakr narrated to us, Ibn Jurayj informed me, Ubayd Allah ibn Umar narrated to me, from Nafi, from Ibn Umar: "That the Messenger of Allah (ﷺ) gave permission to al-Abbas ibn Abd al-Muttalib." He asked the Prophet of Allah (ﷺ) for permission to spend the nights of Mina in Makkah, on account of his duty of providing water (to the pilgrims), "and he gave him permission."