It is makrooh to pluck grey hairs from the head and beard

Grey hairs will be light for the Muslim on the Day of
Resurrection, as is stated in saheeh ahaadeeth. In Sunan al-Tirmidhi
(1634) it is narrated that Ka’b ibn Murrah (may Allaah be pleased with him)
said: I heard the Messenger of Allaah (peace and blessings of Allaah be
upon him) say: “If a person’s hair turns grey in Islam, it will be light for
him on the Day of Resurrection.” Classed as saheeh by al-Albaani in
Saheeh al-Tirmidhi. 

In Musnad Ahmad and Sunan al-Tirmidhi (1635) it
is narrated from ‘Amr ibn ‘Absah (may Allaah be pleased with him) that the
Messenger of Allaah (peace and blessings of Allaah be upon him) said:
“If a person’s hair turns grey for the sake of Allaah, it will be light for
him on the Day of Resurrection.” Classed as saheeh by al-Albaani in
Saheeh al-Tirmidhi. 

Al-Bayhaqi narrated in Shu’ab al-Eemaan that
‘Abd-Allaah ibn ‘Amr (may Allaah be pleased with him) said: The Messenger of
Allaah (peace and blessings of Allaah be upon him) said: “Grey hair is
the light of the Muslim; no man’s hair turns grey in Islam but for every
grey hair he will have one hasanah and will rise one degree in status.”
Silsilat al-Ahaadeeth al-Saheehah (1243). 

This hadeeth has supporting evidence in the hadeeth of Abu
Hurayrah (may Allaah be pleased with him), that the Prophet (peace and
blessings of Allaah be upon him) said: “Do not pluck out grey hairs, for
they will be light on the Day of Resurrection. If a man’s hair turns grey in
Islam, for each grey hair he will have one hasanah and will rise one degree
in status.” Narrated by Ibn Hibbaan. Al-Albaani said in Silsilat
al-Ahaadeeth al-Saheehah (3/247): its isnaad is hasan. 

It was narrated by Ibn ‘Adiyy and by al-Bayhaqi in Shu’ab
al-Eemaan that Faddaalah ibn ‘Ubayd (may Allaah be pleased with him)
said: The Messenger of Allaah (peace and blessings of Allaah be upon
him) said: “Grey hair is light on the face of the Muslim, so whoever wishes,
let him pluck out his light.” Silsilat al-Ahaadeeth al-Saheehah
(1244). 

These ahaadeeth indicate that it is makrooh to pluck out grey
hairs from the head and the beard, and there is no difference between them
in this ruling, because of the general meaning of these ahaadeeth; they do
not apply only to the hair of the head or beard, so it is known that the
ruling applies to both. 

Al-Nawawi said in al-Majmoo’ (1/344): 

It is makrooh to pluck out grey hairs, because of the hadeeth
of ‘Amr ibn Shu’ayb from his father from his grandfather, that the Prophet
(peace and blessings of Allaah be upon him) said: “Do not pluck out
grey hairs, for they will be light on the Day of Resurrection.” It is a
hasan hadeeth that was narrated by Abu Dawood, al-Tirmidhi, al-Nasaa’i and
others with hasan isnaads. Similarly our companions also said that it is
makrooh, as was stated clearly by al-Ghazaali, al-Baghawi and others. If it
were said that it is haraam because the prohibition is stated so clearly,
that would not be far off the mark, and there is no difference between
plucking hairs from the beard or the head. End quote.