[Plucking Grey Hair]

Answer: What I see is that there is no objection to plucking grey hair from the beard, due to the absence of any evidence prohibiting that—unless harm or pain results from it, in which case it is not permissible for a person to cause pain to himself or harm himself.
If it is said: It has been narrated from the Prophet (May Allah bless him and his family and grant them peace) that he forbade al-namṣ (plucking), and al-namṣ is plucking hair?
It is said in reply: Imām al-Manṣūr bi-Allah (Peace be Upon Him) said: The namṣ mentioned in the prohibition is the plucking of the hair of the pubic area.
However, plucking grey hair is not recommended, because of what it contains of admonition and reflection. For when a person looks at his appearance and sees grey hair, his hopes are shortened, and he realizes that after grey hair there is nothing but death. This then calls him to return to Allah, to repent, and to improve his deeds.
It also contains motives for dignity and gravity, for when one with grey hair sees the grey in his face, he adopts dignity even if he was not dignified before, and he becomes shy of engaging in many permissible matters.
It also carries social esteem among people. Indeed, it has come in reports that Allah the Exalted is shy before one who possesses grey hair.
If it is said: It has been narrated in al-Intiṣār: “Plucking grey hair is an innovation,” and: “Grey hair is the light of Allah, so turning away from it is turning away from light.”
And in its marginal notes it is narrated from ʿAmr ibn Shuʿayb, from his father, from his grandfather, that the Prophet Muhammad (May Allah bless him and his family and grant them peace) said: “Do not pluck grey hair, for it is the light of the Muslim.” Narrated by Aḥmad, Abū Dāwūd, al-Tirmidhī, and al-Nasāʾī—along with other reports in this chapter—which indicate that plucking grey hair is prohibited.
We say: What has come in this chapter pertains to manners and etiquette, and does not indicate more than recommendation and desirability. This is clarified by the fact that the commands and prohibitions of the Prophet (May Allah bless him and his family and grant them peace) are divided into two categories:
1- A category related to refined etiquette and good manners, such as cleaning the hair of the head, combing it, oiling it, letting the beard grow, trimming the moustache, clipping the nails, plucking the armpit hair, shaving the pubic hair, and the like—matters which people used to do in the pre-Islamic period and knew before the advent of the Sharīʿah. Thus, whatever commands and prohibitions came regarding these matters are intended for etiquette and recommendation. Included in this is plucking grey hair or dyeing it with henna or with black dye.
Something close to this was mentioned by al-Hādī (Peace be Upon Him) in al-Majmūʿah al-Fākhirah. In this chapter, the commands and prohibitions are not intended as legislative rulings, because these were practices already established before Allah the Exalted sent Islam. People used to wear turbans, let their beards grow, and sometimes dye their grey hair—as did ʿAbd al-Muṭṭalib and others. They would wash their heads, oil them, comb them, part their hair, clip their nails, and so on.
2- A legislative category, which is everything besides that.

Source: Min Thimār al-ʿIlm wa al-Ḥikmah vol.3