Umar bin Muslim bin Ammarah bin Ukaymah said: We were in the bathhouse before the sacrifice, and some people there applied depilatory paste. One of the people of the bathhouse said: Sa'id bin al-Musayyab dislikes this and forbids it. I met Sa'id bin al-Musayyab (may Allah have mercy on him) and mentioned this to him, and he said: O my nephew, this is a hadith that has been forgotten and abandoned. Umm Salamah (may Allah be pleased with her), the wife of the Prophet (peace and blessings be upon him), narrated to me that the Messenger of Allah (peace and blessings be upon him) said: "Whoever has an animal to sacrifice and intends to slaughter it, then when he sees the new moon of Dhu al-Hijjah, let him not cut his hair or nails until he has offered the sacrifice."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الضحايا / 19043