Allah the Almighty says:
They said: "O Dhul-Qarnain! Verily Ya'juj and Ma'juj (Gog and
Magog) are doing great mischief in the land. Shall we then pay you a
tribute in order that you might erect a barrier between us and them?"
He said: "That (wealth, authority and power) in which my Lord had
established me is better (than your tribute). So help me with strength
(of men), I will erect between you and them a barrier. "Give me pieces
(blocks) of iron;" then, when he had filled up the gap between the two
mountain-cliffs, he said: "Blow;" then when he had made them (red as)
fire, he said: "Bring me molten copper to pour over them." So they
(Ya'juj and Ma'juj (Gog and Magog) could not scale it or dig through it.
(Dhul-Qarnain) said: "This is a mercy from my Lord, but when the
Promise of my Lord comes, He shall level it down to the ground. And
the Promise of my Lord is ever true".
(Al-Kahf, 94-98)
And,
Until, when Ya'juj and Ma'juj (Gog and Magog) are let loose
(from their barrier), and they swoop downfrom every mound.
(Al-Anbiya, 96)
No doubt; Gog and Magog are from among the children of Adam 
.
In proof of this, comes the Hadith that is transmitted in the two
Sahihs (Bukhari and Muslim) from Al-A'mash, after Abu Salih, after Abu Sa'id Al-Khudri
who narrated the Prophet 
to have said:
Allah 
will say (on the Day of Resurrection), 'O Adam!' Adam will reply, 'Labbaik wa Sa'daik,
and all the good is in Your Hand.' Allah will say: 'Bring out the people of the fire.'
Adam will say: 'O Allah ! How many are the people of the Fire?' Allah will reply:
'From every one thousand, take out nine-hundredand ninety-nine.' At that time
children will become hoary headed, every pregnant female will have a
miscarriage, and one will see mankind as drunken, yet they will not be drunken,
but dreadful will be the Wrath of Allah ."
The Companions of the Prophet asked:
"O Allah's Messenger! Who is that (excepted) one?"
He said, "Rejoice with glad tidings; one person will be from you and one
thousand will be from Gog and Magog."
The Prophet further said, "By Him in Whose Hands my life is, hope that you will be one-fourth
of the people of Paradise." We shouted, "Allahu Akbar!"
He added, "I hope that you will be one-third of the people of
Paradise. We shouted, "Allahu Akbar!"
He said, "I hope that you will be half of the people of Paradise." We shouted, "Allahu Akbar!"
He further said, "You (Muslims) (compared with non Muslims) are like a black hair in the skin of a white ox or like
a white hair in the skin of a black ox (i.e. your number is very small as compared with theirs)."
(Al-Bukhari and Muslim)
This Hadith denotes the numerousness of their numbers and that they are a
hundred-fold the number of all mankind. Moreover, they are from among the
offspring of Nuh (Noah) in particular for Allah the Almighty
informs us in His Glorious Qur'an that Nuh invoked Him
against the people of the earth saying:
And Nuh (Noah) said: "My Lord! Leave not one of the disbelievers on the earth!"
(Nuh, 26)
And, Allah the Almighty Himself says:
Then We saved him and those with him in the ship.
(Al-Ankabut, 15)
And,
And, his progeny, them We made the survivors.
(As-Saffat, 77)
This is in addition to the Hadith transmitted in Imam
Ahmed's Musnad and the Sunan of Abu Dawud that mentioned: that there were
three sons born to Nuh : Shem, Ham and Japheth. Shem
was the father of the Arabs; Ham was the father of the Sudan; and Japheth was
the father of the Turk (The Turk here does not mean those of Turkey. [Translator]).
Moreover, Gog and Magog are just a part of the Turk
from among the Mangols who were stronger and spread mischief in the land.
Some people claimed that Gog and Magog were created out of the semen of
Adam that mixed with the earth and thus they were not
from Eve. But, this claim -which was held by Sheik Abu Zakariya An-Nawawi in
his explanation of Sahih Muslim and by other scholars who declared it to be
weak and strange - is too weak. As, there is not any proof on this and moreover,
it contradicts the obvious text of the Glorious Qur'an - mentioned earlier - that all
mankind of today are from the offspring of Nuh .
In addition, some people claimed that they (Gog and Magog) are of different
shapes and figures: some are as tall as palm-trees, some are too short, and
some take one of their ears as a bed and the other as a cover or blanket.
However, all these claims are groundless and cannot stand the slightest
refutation. But, the correct view is that: they are from among the children of
Adam and that they bear the same qualities and shapes.
Allah's Prophet said:
Allah created Adam , making him 60 cubits tall. When He created him, He said to him,
"Go and greet that group of
angels, and listen to their reply, for it will be your greeting (salutation) and the
greeting (salutations of your offspring."
So, Adam said (to the angels), As-Salamu Alaikum (i.e. Peace be upon you). The angels said, "As-Salamu Alaika
wa Rahmatu-l-lahi" (i. e. Peace and Allah's Mercy be upon you). Thus the angels
added to Adam's salutation the expression, 'Wa Rahmatu-l-lah.'
Any person who will enter Paradise will resemble Adam (in appearance and figure). People have
been decreasing in stature since Adam's creation.
This Hadith blocks the way before those who falsely claim things that are groundless.
A Very Important Question
If it is said: How does the previously mentioned Hadith - that was agreed upon -
denote that they will be treated as ransom for the Believers on the Day of
Resurrection and that they will enter Hell fire, while no Messengers were sent to
them and Allah the Almighty says:
And We never punish until We have sent a Messenger (to give warning)
(Al-Isra, 15)
The answer is that: They will never be punished until they are given
warning. Thereupon, if they were existing before the time of Prophet Muhammad
and Messengers were sent to them, thus, they were given
warning. And, if no Messengers were sent to them, they would be treated as
"People of the Fitrah" and those to whom the Message of Islam did not reach or
be conveyed. However, it is indicated by the Hadith transmitted by some of the
Companions of the Prophet that he said:
Those and the
like will be tested on the pathways of the Resurrection: and whoever responds to
the caller, he will enter Paradise. And, whoever refuses, he will enter the Fire.
However, testing them neither necessitates their salvation, nor contradicts with
the saying that they will enter Hell fire. For Allah the Almighty reveals to His
Prophet what He wills of the Unseen, and hence, He
informed him that they will be from among the people of Hell and that their
nature denies the truth and submission thereto, as they do not respond to the
caller till the Day of Judgement. This indicates that, they would be more stubborn
in rejecting the truth if they were to come to know it in this present life. In the
pathways of Resurrection, some of those who used to belie the truth in the
present life will submit themselves to the truth.
Almighty Allah says:
And if
you only could see when the Mujrimun (criminals, disbelievers,
polytheists, sinners) shall hang their heads before their Lord (saying):
"Our Lord! We have now seen and heard, so send us back (to the
world), that we will do righteous good deeds. Verily! We now believe
with certainty ".
(As-Sajdah, 12)
However, the Prophetic Hadith indicating
that the Prophet invited them on the Night Journey to
embrace Islam and they refused, this Hadith is an invented and fabricated one.
The one who fabricated it was the liar, Amr Ibn As-Subh.
The (Dam) Barrier
It was mentioned earlier that Dhul-Qarnain has built it out of iron and copper
and elevated it to a very high point that is equal to the very lofty mountains.
However, there is no on earth an equal building in terms of loftiness or
benefiting to mankind. Imam Al-Bukhari transmitted in his Sahih the following
Hadith saying:
A man told the Prophet that he had seen
the dam (of Gog and Magog). The Prophet asked: How did
you find it? The man said: I found it like Al-Burd Al-Muhabbar (stripped
garments). The Prophet said: You have seen it like that.
In Ibn Jarir's exegesis of the Quran, a slight different narration was reported by
Qatadah 
who said:
I was told that a man said: O Allah's Messenger ! I have
seen the dam of Gog and Magog. The Prophet said:
Describe it to me. The man said: It looked like stripped garments, with red and
black stripes. The Prophet said: You have seen it.
It was mentioned that the Caliph, Al-Wathiq sent some messengers with
messages to different kings to allow them travelling from one country to another
till they reach the dam and stand on its reality. When they came back to the
Caliph, they described it to him saying that it has a huge door with many locks.
It is a very high and tight building and that the remnants of its building materials
and tools are kept there in a tower. Also, there are still guards keeping an eye on
it. They added that its location is on the northern-east side of the earth. It was
also said that their land is very spacious and that they live on farming and
hunting and that their numbers are countless.
How can we compromise between the Quranic Verse that reads:
So they, Yajuj and Majuj (Gog and Magog) could not scale it or dig through
it.
(Al-Kahf, 97)
And the Prophetic Hadith that is transmitted by Imam Al-Bukhari and
Imam Muslim on the authority of Mother of the Believers, Zainab
Bint Jahsh 
as saying:
That the Prophet once came to her in a state of fear and said: "None has the right
to be worshipped but Allah . Woe unto the Arabs from a danger that has come
near. An opening has been made in the wall of Gog and Magog like this," making
a circle with his thumb and index finger. Zainab Bint lahsh said: "O Allah's
Messenger ! Shall we be destroyed even though there are pious persons among
us?" He said: "Yes, when the evil persons will increase."
And in another narration the Prophet said:
Allah has made an opening in the wall of the Gog and Magog (people) like this, and he made with his hand
(with the help of his fingers).
(Al-Bukhari and Muslim)
The answer is that, this means one of two things: the first is that this is an
indication of the opening of gates of evil and turmoil and hence, this is a mere
example set for us. The second view considers this as narrating a concrete
matter for His Statement, "So they (Ya'juj and Ma'juj (Gog and Magog)]
could not scale it or dig through it", i.e. at their time for the sentence is in
the past tense, the matter which does not contradict the possibility of its taking
place in the future with the Permission of Allah the Almighty.
But, as for the
other Hadith that is narrated by Imam Ahmed in his Musnad that the Prophet
said:
Verily, Gog and Magog dig through the dam every
day, till they could see the sun rays (through it), their leader would say: "Go back
and you will finish it tomorrow." On the next day, they find it as strong as
before. Till when their appointed term comes and Allah desires to send them
against mankind, they dig it till they could see the sun rays (through it) and their
leader says: "Go back and you will finish it tomorrow, if Allah wills!" On the next
day, they find it as they had left the day before and they dig through it and come
against mankind. They will drink (every drop of water they pass by). The people
will resort to strongholds. And, Gog and Magog will throw their arrows towards
the sky. When they come back to them stained with what looks like blood, they
will say: "we have defeated the people on earth and those in the heaven as well."
Then, Allah the Almighty sends against them worms in their necks that kill them
all.
Allah's Messenger said:
"By Whom in Whose Hand
Muhammed's soul rests! Living creatures of the earth would go fat and be
thankful due to eating their flesh and (drinking their) blood."
Imam Ahmed
transmitted it also on the authority of Hasan Ibn Musa after Sufyan after
Qatadah . At-Tirmidhi transmitted the same Hadith on the authority of Abu
Awanah after Qatadah , then he said: it is a Strange Hadith that reached us from
none but this Chain of Transmission.