Fiqh-us-Sunnah Volume 5, Hajj and ‘Umrah, Fiqh 5.117A.
Section : Clipping one’s Nails and Shortening Moustaches.
It is desirable for those who shave or cut short their hair (as pilgrims) to also clip their finger nails and shorten their moustaches. Whenever Ibn ‘Umar shaved or cut short his hair in Hajj or ‘Umrah, he would always clip his finger nails and shorten his moustaches.
Ibn al-Munzhir said, “It is confirmed that when the Prophet (peace be upon him) shaved or cut short his hair he clipped his finger nails as well.”