Umm Salamah (May Allah be pleased with her) said:
The Messenger of Allah ﷺ said, "When anyone of you intends to sacrifice the animal and enter in the month of Dhul-Hijjah, he should not get his hair cut or nails pared till he has offered his sacrifice."

[Muslim].

عن أم سلمة رضي الله عنها قالت قال رسول الله ﷺ : "من كان له ذبح يذبحه، فإذا أهل هلال ذي الحجة، فلا يأخذن من شعره ولا من أظفاره شيئًا حتى يضحي" ((رواه مسلم)).