It is narrated from Sayyidah Umm Salamah (may Allah be pleased with her); she said that the Messenger of Allah (peace and blessings be upon him) said: "Whoever has an animal for sacrifice that he intends to slaughter, then when the crescent of Dhu al-Hijjah appears, let him not take anything from his hair or his nails until the animal has been slaughtered."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 19861