Musnad Abu Ya'la al-Mawsili 110:59

Zuhayr narrated to us, Ibn 'Uyaynah narrated to us, 'Ubayd Allah ibn Abi Yazid narrated to us, he said: I heard Ibn 'Abbas saying: I was among those whom the Prophet, may Allah bless him and grant him peace, sent ahead with the weak members of his family from Muzdalifah to Mina.