Firstly:
Letting the beard grow (’i`fa’) is enjoined by the Sunnah, as in the hadith of Ibn `Umar, according to which the Prophet (blessings and peace of Allah be upon him) said: “Trim the moustache and let the beard grow.” Narrated by al-Bukhari, 5893, and Muslim, 259.
What is meant by leaving the beard grow is letting it be and allowing it to grow, and not trimming it. It is proven in Arabic that the word “’u`fu’” (translated here as “let… grow”) means to leaving something alone and allowing it to become abundant.
Ibn al-Athir (may Allah have mercy on him) said:
In this hadith, it says that the Prophet (blessings and peace of Allah be upon him) instructed them to let their beards grow, which means leaving the hair of the beard to grow and become abundant, and not trimming it like the moustache. This comes from the phrase `afa ash-shay’ [the thing grew] which refers to a thing growing and increasing.
End quote from An-Nihayah fi Gharib al-Hadith, 3/266.
This is the meaning that all commentators on the hadith referred to.
This understanding is confirmed by other authentic narrations of this hadith from Ibn `Umar and from other Sahabah, which explain one another.
Al-Bukhari (5892) narrated from Ibn `Umar that the Prophet (blessings and peace of Allah be upon him) said: “Be different from the polytheists; let your beards grow and trim your moustaches.”
Muslim (259) narrated that Ibn `Umar said: The Messenger of Allah (blessings and peace of Allah be upon him) said: “Be different from the polytheists: trim your moustaches and let your beards grow.”
And Muslim (260) narrated that Abu Hurayrah said: The Messenger of Allah (blessings and peace of Allah be upon him) said: “Trim the moustache and let the beard grow: be different from the Zoroastrians.”
Imam Ahmad narrated in Al-Musnad (36/613) that Abu Umamah said: The Messenger of Allah (blessings and peace of Allah be upon him) came out to some old Ansari men whose beards had turned white, and said: “O Ansar, dye [your beards] red or yellow, and be different from the People of the Book.”
He [Abu Umamah] said: We said: O Messenger of Allah, the People of the Book trim their beards and let their moustaches grow.
The Prophet (blessings and peace of Allah be upon him) said: “Trim your moustaches and let your beards grow; be different from the People of the Book.” The commentators on Al-Musnad classed its isnad as authentic (sahih).
An-Nawawi (may Allah have mercy on him) said:
There are five reports, which use different words referring to letting the beard grow.
What is meant by all of them is to leave the beard alone. This is what the hadith appears to mean, on the basis of the wording used; this is what a number of our companions and other scholars say.
End quote from Sharh Sahih Muslim, 3/151.
Not one of the scholars said that what is meant “’u`fu’” (translated here as “let… grow”) is to cut and remove the beard; rather they clearly stated that the beard is to be left alone, to the extent that al-Kamal ibn al-Humam al-Hanafi said in Fat-h al-Qadir (2/348):
As for trimming the beard to be shorter than what one can grasp in one’s fist, as some Moroccans and effeminate men do, no scholar permits that. End quote.
Imam Abu Muhammad ibn Hazm said in Maratib al-Ijma`, p. 157:
The scholars are agreed that shaving off all of the beard is mutilation and is not permitted. End quote.
Secondly:
Letting the beard grow is regarded as one of the characteristics of the fitrah (sound human nature). A hadith about that was narrated by Imam Muslim (261) from Waki`, from Zakariya ibn Abi Za’idah, from Mus`ab ibn Shaybah, from Talq ibn Habib, from `Abdullah ibn az-Zubayr, from `A’ishah, who said: The Messenger of Allah (blessings and peace of Allah be upon him) said: “Ten things are part of the fitrah: trimming the moustache, letting the beard grow, using the siwak, rinsing the nose with water, cutting the nails, washing the finger joints, plucking the armpit hairs, shaving the pubic hair, and washing the private parts with water.”
Zakariya said: Mus`ab said: I have forgotten the tenth, but it may have been rinsing the mouth with water.
Qutaybah added: Waki` said: Washing the private parts with water refers to washing after relieving oneself (istinja’).
The one who said that all these things refer to removing something from the body, like the nails, or removing dirt by means of it, like rinsing the nose and the like, so what is meant by “’i`fa’” of the beard comes under the same heading, namely removing it – this is an invalid understanding and is to be rejected; none of the scholars ever said that.
What does the one who holds this odd and false view say about using the siwak and rinsing the nose with water? What does this have to do with trimming or removing the beard (as he understood it)? Rather each of these practices has a way in which it is to be done, and it cannot be compared with the other practices mentioned. In some cases hair is to be removed with a razor, such as the pubic hair, and in other cases it is to be plucked and not shaved, according to what is narrated in the hadith, such as the armpit hair. In some cases something is to be trimmed, such as the moustache, and in other cases it is to be left alone, such as the beard, according to what we have quoted above from the scholars. And some of these practices have nothing to do with trimming or removing something or leaving it alone, like the rest of the practices mentioned.
Moreover, what would the one who holds this upside-down view say about the practice of the Prophet (blessings and peace of Allah be upon him) concerning his beard, when Muslim (2344) narrated that Jabir ibn Samurah said: The Messenger of Allah (blessings and peace of Allah be upon him) had a thick beard?
Thirdly:
The religious texts enjoin being different from the Zoroastrians and the People of the Book, who used to trim their beards and let their moustaches grow. Our religion, which is in harmony with sound human nature and cleanliness, has taught us to differ from them.
Imam Muslim (260) narrated that Abu Hurayrah said: The Messenger of Allah (blessings and peace of Allah be upon him) said: “Trim the moustache and let the beard grow: be different from the Zoroastrians.” Al-Hafiz Ibn Hajar (may Allah have mercy on him) said:
The words “be different from the polytheists” – and “be different from the Zoroastrians” in the hadith of Abu Hurayrah narrated by Muslim – are what is meant in the hadith of Ibn `Umar. They [the polytheists and Zoroastrians] used to trim their beards, and some of them would shave them off.
End quote from Fat-h al-Bari, 10/349.
Imam Ahmad narrated in Al-Musnad (36/613) that Abu Umamah said: The Messenger of Allah (blessings and peace of Allah be upon him) came out to some old Ansari men whose beards had turned white, and said: “O Ansar, dye [your beards] red or yellow, and be different from the People of the Book.”
He [Abu Umamah] said: We said: O Messenger of Allah, the People of the Book trim their beards and let their moustaches grow.
The Prophet (blessings and peace of Allah be upon him) said: “Trim your moustaches and let your beards grow; be different from the People of the Book.” The commentators on Al-Musnad classed its isnad as authentic (sahih)..
By being different from the Zoroastrians and the People of the Book, the Muslims would also be different from the polytheist Arabs, because even though they let their beards grow, it is not known that they used to trim their moustaches in the Islamic manner.
Fourthly:
According to the scholars, “’i`fa’” of the beard definitely means letting it grow freely, but many of the scholars are of the view that there is nothing wrong with removing and trimming unruly parts of the beard.
It says in Al-Ikhtiyar li Ta`lil al-Mukhtar (4/167), which is a book of Hanafi jurisprudence:
With regard to “’i`fa’” of the beard: Muhammad said, quoting from Abu Hanifah: It means leaving it to grow until it becomes thick and abundant. Shortening it somewhat is Sunnah; what that means is grabbing hold of the beard and cutting whatever goes beyond that fistful, because the beard is an adornment, and its becoming thick and long makes it more beautiful, but if it becomes too long and unruly, that is contrary to the Sunnah. End quote.
Al-Qurtubi (may Allah have mercy on him) said:
As for “’i`fa’” of the beard, it means letting it grow and become thick…
It is not permissible to shave it, pluck it or cut a lot from it.
As for cutting flyaway hairs and whatever spoils one’s appearance to the extent that it makes one stand out, with long hair flying in all directions, that is good according to Malik and others of the early generations.
End quote from Al-Mufhim, 1/512-513.
An-Nawawi (may Allah have mercy on him), who was a Shafa`i, said:
“’i`fa’” of the beard is part of the fitrah (sound human nature). Al-Khattabi and others said: It means leaving it alone without cutting it. It is disapproved for us to cut it like the non-Arabs do. He said: The Persian style was to cut the beard and let the moustache grow.
Al-Ghazali said in Al-Ihya’: The early generations differed regarding the beard when it becomes very long. It was said that there is nothing wrong with taking hold of it and cutting what is below the fistful. This was the practice of Ibn `Umar and, later, of some of the Tabi`in, and ash-Sha`bi and Ibn Sirin regarded it as a good practice.
Al-Hasan and Qatadah regarded it as disliked, and they said: He should leave it to grow without touching it, because the Prophet (blessings and peace of Allah be upon him) said: “Let your beards grow.” Al-Ghazali said: It is allowed to trim it provided it does not lead to cutting it so much that it ends up like shortening it, because when it is too long it may spoil one’s appearance. That is the view of al- Ghazali. However, the the correct view is that it is disliked to remove anything from the beard; rather one should leave it alone to grow naturally, because of the authentic hadith: “Let your beards grow.”
End quote from Al-Majmu`, 1/290.
Shaykh al-Islam Ibn Taymiyah (may Allah have mercy on him) said:
As for letting the beard grow, that means that it should be left alone, but if a person trims anything that is longer than a fistful, that is not disliked. This was stated by Imam Ahmad, on the basis of what was narrated from Ibn `Umar. He may also remove any flyaway hairs from the beard.
End quote from Sharh al-‘Umdah – Kitab at-Taharah, 1/236.
Thus it becomes clear that removing a little from the beard in such a way that it still looks thick and long is a well-known view among the scholars and early generations of the ummah. But regarding the limit of how much may be removed, the strongest view (based on the soundest reports) is that the Muslim may remove what is more than the fistful, as was narrated from Ibn `Umar (may Allah be pleased with him) and others.
Al-Bukhari (5892) narrated from Ibn `Umar that when he did Hajj or `umrah, he would grab hold of his beard and whatever was longer than that fistful, he would cut.
If the one who said [what is mentioned in the question] was referring to this view, it is a view that carries weight and there is no blame on the one who does that. But what you told us he said does not suggest that he holds that view, or even comes close to it.
And Allah knows best.