What the Person Offering the Sacrifice Avoids During the First Ten Days of Dhul-Hijjah

Whoever intends to offer a sacrifice (udhiyah), once the month of Dhul-Hijjah begins, refrains from taking anything from his hair, his nails, or his skin until he offers the sacrifice, because of the saying of the Prophet ﷺ: «إذا أُهِلَّ هلالُ ذي الحجة فلا يأخذنّ من شعره ولا من أظفاره شيئاً حتى يُضحّي». This is specific to the one offering the sacrifice, not to those on whose behalf the sacrifice is offered.

Source:حديث أم سلمة، رواه مسلم؛ وفتوى ابن باز [خلاف: الجمهور على الكراهة، والحنابلة على التحريم]