What is the meaning of the words of the Prophet (blessings and peace of Allah be upon him): “I have been given the Qur’aan and something like it along with it”?

This hadeeth is one of the sound hadeeths that are proven to
be from the Messenger of Allah (blessings and peace of Allah be upon him).
What is meant by the words “ and something like it along with it” is that
Allah has given him another revelation, which is the Sunnah which explains
the Qur’aan and clarifies its meanings, as Allah, may He be glorified and
exalted, says (interpretation of the meaning):

“And We have also sent down unto you (O Muhammad
صلىالله عليه وسلم)
the Dhikr [reminder and the advice (i.e. the Qur’aan)], that you may explain
clearly to men what is sent down to them, and that they may give thought”

[al-Nahl 16:44]

So Allah revealed the Qur’aan to him and also the Sunnah,
which is the hadeeth which are proven to be from him (blessings and peace of
Allah be upon him), which have to do with prayer, zakaah, fasting, Hajj and
other religious and worldly matters. The Sunnah is a second revelation which
Allah revealed to him to complete the message, and he (blessings and peace
of Allah be upon him) expressed that in the hadeeths which he explained to
the ummah in word and in deed and by means of his approval, such as his
saying: “Deeds are but by intentions, and each man will have but that which
he intended”; and “The prayer of one of you will not be accepted if he
breaks wind until he does wudoo’”; and “No prayer is accepted without
purification, and no charity is excepted from wealth acquired by treacherous
means”; and “The five daily prayers, one Ramadan to another, and one Jumu’ah
to another, are expiation for the sins that come in between them, so long as
you do not commit major sins.” And there are many other saheeh hadeeths
which speak of everything that a person needs to know and which have to do
with explanation of the Book of Allah. This revelation is a revelation that
Allah revealed to him, of which the Prophet (blessings and peace of Allah be
upon him) spoke and explained to the ummah. The meanings are revelation from
Allah, and the words are from the Prophet (blessings and peace of Allah be
upon him), like the words quoted above: “Actions are but by intention…”
and like his words: “The two parties to a transaction have the option (of
cancelling it) so long as they have not yet parted…” 

The second revelation which was given to the Prophet
(blessings and peace of Allah be upon him) also includes the sacred hadeeth
(hadeeth qudsi) which the Messenger transmitted from his Lord, may He be
glorified and exalted. They are revelation from Allah and are His words, but
they do not come under the same ruling as the Qur’aan, such as what the
Prophet (blessings and peace of Allah be upon him) said, narrating it from
his Lord: “O My slaves, I have forbidden injustice to Myself, and I have
made it forbidden among you, so do not wrong one another. O My slaves, all
of you are misguided except those whom I guide, so ask Me for guidance, I
will guide you…” this is a lengthy hadeeth, which was narrated by Muslim
in his Saheeh from Abu Dharr al-Ghifaari (may Allah be pleased with
him). All of that is included in the words of Allah (interpretation of the
meaning):

“By the star when it goes down (or vanishes).

2. Your companion (Muhammad
صلى الله عليه وسلم)
has neither gone astray nor has erred.

3. Nor does he speak of (his own) desire.

4. It is only a Revelation revealed”

[al-Najm 53:1-4]