بسم الله الرحمن الرحيم

Umm Salama Radi allahu anha se rivayat hai ki RasoollAllah Sallallahu alaihi wa sallam ne farmaya Jiskey paas janwar ho zabah karne ke liye aur Zil Hijja ka chand aa jaye (ya jab Dhu’l-Hijja ka mahina aa jaye) to apne Baal na katwaye aur na Nakhun tarashe jab tak qurbani na kar le.
{Sahih Muslim , Vol 5, 5121}

English Translation:
Umm Salama, the wife of Allah’s Apostle may peace be upon him reported Allah’s Messenger may peace be upon him have said: He who has a sacrificial animal with him whom (he intends) to offer as sacrifice, and he enters the month of Dhu’I-Hijja, he should not get his hair cut or nails trimmed until he has sacrificed the animal.
{Sahih Muslim, Book 022, Number 4873}