Musnad Ahmad 1156:99

Hassan narrated to us, he said: Ibn Lahi'ah narrated to us, he said: Sa'id ibn Abi Hilal narrated to me, from 'Amr ibn Muslim al-Junda'i, that he said: Ibn al-Musayyib informed me, that Umm Salamah, the wife of the Prophet, may Allah bless him and grant him peace, informed him, from the Messenger of Allah, may Allah bless him and grant him peace, that he said—Abu 'Abd al-Rahman—'Abdullah ibn Ahmad—said: My father said, and Muhammad ibn 'Amr—meaning Ibn 'Alqamah—said: From 'Amr ibn Muslim ibn 'Ammar ibn Akimah, that he said: If he said it. Thus my father said in the hadith: "Whoever intends to offer a sacrifice, let him not trim his nails, and let him not shave any of his hair during the first ten days of Dhu al-Hijjah."