Abstaining from Hair and Nails in the Ten Days of Dhu al-Hijjah: The Agent or the Principal

Question:
Honorable Shaykh, may Allah grant you success. He says: Who is the one who abstains from cutting his hair and nails during the ten days of Dhu al-Hijjah? Is it the agent or the principal regarding the sacrifice?

Answer:
The one who abstains is the one who wants to sacrifice on his own behalf, whether he is with others or alone. Whoever wants to sacrifice on his own behalf, he abstains. This is what is mentioned in the hadith. The jurists say: "Whoever wants to sacrifice, or is sacrificed for, or is sacrificed for on his behalf." What is the evidence for that? Yes, but the one who wants to sacrifice on his own behalf, whether alone or as a partner in a sacrifice, does not cut [his hair or nails] until the end. Yes.