How should we greet scholars and leaders?

Firstly: 

The correct way to greet scholars is to greet them with
salaam and shake their hand. Many ahaadeeth have been narrated concerning
the virtue of these actions. It is also permissible to kiss their heads or
hands sometimes, but that should not be taken as a habit or custom,
especially if it is done instead of shaking hands. 

With regard to embracing, that is permissible when someone
comes from a journey or after a long absence, or to express one’s deep love
for the sake of Allaah and so on. 

Muslim (54) narrated that Abu Hurayrah (may Allaah be pleased
with him) said: The Messenger of Allaah (peace and blessings of Allaah
be upon him) said: “By the One in Whose hand is my soul, you will not enter
Paradise until you believe, and you will not believe until you love one
another. Shall I not tell you something which, if you do it, you will love
one another? Spread the greeting of salaam amongst yourselves.” 

And it was narrated that Qataadah said: I said to Anas: Did
the companions of the Prophet (peace and blessings of Allaah be upon
him) shake hands with one another? He said: Yes. Narrated by al-Bukhaari,
5908. 

And it was narrated that Anas said: When the companions of
the Prophet (peace and blessings of Allaah be upon him) met they would
shake hands with one another, and if they came from a journey they would
embrace one another. 

Narrated by al-Tabaraani in al-Awsat (1/37); classed
as saheeh by Shaykh al-Albaani in al-Silsilah al-Saheehah, 2647. 

It was narrated from ‘Awn ibn Abi Juhayfah that his father
said: When Ja’far came after he had migrated to Abyssinia, the Prophet
(peace and blessings of Allaah be upon him) embraced him and kissed him
between the eyes. 

Narrated by al-Tabaraani in al-Kabeer (2/108); there
are many corroborating reports which were mentioned by al-Haafiz ibn Hajar
in al-Talkhees al-Habeer, 4/96/ it was classed as saheeh by Shaykh
al-Albaani in al-Silsilah al-Saheehah, 2657. 

It was narrated that Usaamah ibn Shareek said: We stood up
for the Prophet (peace and blessings of Allaah be upon him) and kissed
his hand. 

Narrated by Abu Bakr ibn al-Muqqari in Juz’ Taqbeel al-Yad,
p. 58. Al-Haafiz ibn Hajar said: Its isnaad is qawiy. Fath al-Baari,
11/56 

Shaykh Muhammad Naasir al-Deen al-Albaani said: 

I say: This indicates that the Sahaabah differentiated
between whether a person was present or travelling in the manner in which
they greeted him. In the first case (when a person was a resident) they
shook hands, and in the second case (when a person had come from travelling)
they embraced him. Hence I used to avoid embracing when not travelling. In
particular, in the first volume of al-Silsilah (no. 160) I narrated a
hadeeth in which the Prophet (peace and blessings of Allaah be upon
him) forbade bowing, embracing and kissing. Then when I prepared that volume
for reprinting, I re-examined this hadeeth and noticed that the word
embracing is not mentioned in the corroborating reports on the basis of
which I had classed the hadeeth as qawiy, so I took it out, as will be seen
in the new edition in sha Allaah which will be published shortly, praise be
to Allaah. 

When I realized that it was weak, I felt comfortable about
taking it out, praise be to Allaah. In particular I saw that Ibn al-Teehaan
al-Ansaari embraced the Prophet (peace and blessings of Allaah be upon
him), according to the hadeeth that speaks of the Prophet (peace and
blessings of Allaah be upon him) coming out to the house of Ibn al-Teehaan
(may Allaah be pleased with him), which is narrated in al-Shamaa’il
al-Muhammadiyyah (no. 113, p. 79 – Mukhtasar al-Shamaa’il). But
here it indicates that this is permissible sometimes, not that it is to be
done always, as if it were a Sunnah, and as is the case with shaking hands,
so attention should be paid to that. 

I noted that Imam al-Baghawi spoke about the differentiation
mentioned above, and I think it will be very useful to quote him here. He
(may Allaah have mercy on him) said in Sharh al-Sunnah (12/293),
after mentioning the hadeeth of Ja’far and others which may appear to be
contradictions: 

With regard to the kind of embracing and kissing that is
makrooh, it is that which is done by way of flattery and veneration when a
person is not travelling. The kind that is permitted is that which is done
when bidding farewell and when a person returns from a journey, and when
meeting someone after not seeing him for a long time and when there is
intense love for the sake of Allaah. What is to be kissed is not the mouth
but rather the hand, head and forehead. 

It is makrooh to do that when one is not travelling as far as
I can see, because one meets people frequently and not everyone deserves
that. If a man does that to some people and not to others, those whom he
ignores will be upset by that and will think that he is falling short and
neglecting their rights. The best greeting is the handshake. End quote. 

It should be noted that some of the imams, such as Abu
Haneefah and his companion Muhammad, are of the view that embracing is
makrooh; al-Tahhaawi narrated this from them, which is opposite to the view
of Abu Yoosuf. 

Imam Maalik also regarded it as makrooh. In al-Adaab
al-Shar’iyyah (2/278) it says: 

Maalik regarded it as makrooh to embrace one who comes from a
journey and said it is a bid’ah (innovation). He explained the fact that the
Prophet (peace and blessings of Allaah be upon him) did that to Ja’far
when he came as being a unique case. Sufyaan said to him: You cannot regard
it as a unique case without evidence and Maalik fell silent. Al-Qaadi said:
The fact that he fell silent indicates that he accepted what Sufyaan said
and agreed with him. This is the correct view, so long as there is no
evidence that this is a unique case. 

We have referred above to the view of Imam al-Baghawi who
said that there should be no kissing on the mouth. Shaykh Ibn Muflih
explained the reason for that in al-Adaab al-Shar’iyyah (2/275) where
he said: 

It is makrooh to kiss on the mouth, because it is rarely done
out of respect. 

And it seems to me that there is another reason, which is
that it is not narrated that the salaf did that; if it were good they would
have done it before us. How well the poet spoke when he said: 

All goodness is in following those who came before and all
evil is in the innovations of those who came later. 

Al-Silsilah al-Saheeh, vol. 6,
section 1 (305-307). 

And the Shaykh also said: 

With regard to kissing the hand, there are many ahaadeeth and
reports concerning that, which when taken together indicate that this is
proven from the Messenger of Allaah (peace and blessings of Allaah be
upon him). We think that it is permissible to kiss the hand of the scholar
if the following conditions are met: 

1.That it does not become a
custom to such an extent that the scholar habitually stretches out his hand
to his students and they habitually seek blessing by kissing his hand,
because although the hand of the Prophet (peace and blessings of Allaah
be upon him) was kissed, that happened rarely, and such matters cannot be
taken as a Sunnah to be done regularly, as is well known from the basic
principles of fiqh.

2.That should not make the
scholar feel arrogant towards others or admire himself, as happens among
many shaykhs nowadays.

3.That should not lead to
abandoning any well known Sunnah, such as shaking hands, which is prescribed
because of the words and actions of the Prophet (peace and blessings of
Allaah be upon him) and is a shar’i means of the sins of those who shake
hands being erased, as is narrated in more than one hadeeth. It is not
permissible to supercede it or ignore it for another habit which, at best,
is permissible.

Al-Silsilah al-Saheehah, 1/302. 

Secondly: 

With regard to bowing, that is not permissible when meeting
anyone, whether he is a scholar or not. 

Shaykh al-Islam Ibn Taymiyah said: 

With regard to bowing when meeting, it is forbidden as it is
narrated in al-Tirmidhi that they asked the Prophet (peace and
blessings of Allaah be upon him) about a man who meets his brother and bows
to him. He said: “No, because it is not permissible to bow or prostrate to
anyone except Allaah, may He be glorified. That may have been done by way of
greeting under a law other than ours, as in the story of Yoosuf – “…and
they fell down before him prostrate. And he said: “O my father! This is the
interpretation of my dream aforetime!”  [Yoosuf 12:100].  

But in our sharee’ah it is not permissible to prostrate to
anyone except Allaah. Indeed it is forbidden to stand as the Persians used
to stand for one another – so what about bowing and prostrating? And a
slight bow (as opposed to the full bow as in prayer) is also included in
this prohibition. 

Majmoo’ al-Fataawa, 1/377 

And he said: 

With regard to lowering one’s head before the senior shaykhs
or kissing the ground etc, these are matters concerning which there is no
dispute among the imams that they are haraam. Indeed, simply bowing to
anyone other than Allaah is forbidden. In al-Musnad and elsewhere it
is narrated that when Mu’aadh ibn Jabal (may Allaah be pleased with him)
came back from Syria he prostrated to the Prophet (peace and blessings
of Allaah be upon him) and he said: “What is this, O Mu’aadh?” he said: “O
Messenger of Allaah, I saw them in Syria prostrating to their bishops and
patriarchs, and they narrated that from their Prophets.” He said, “They are
lying, O Mu’aadh. If I were to command anyone to prostrate to anyone else I
would have told the women to prostrate to their husbands because of the
greatness of their rights over them. O Mu’aadh, do you think that if you
pass by my grave you will prostrate?” He said, “No.” He said: “Do not do
that.” 

In conclusion, standing, sitting, bowing and prostrating are
all due to the One God, the Creator of the heavens and the earth. Whatever
is a right only for Allaah, no one else can have a share in it, such as
swearing by anyone other than Allaah etc. 

Majmoo’ al-Fataawa, 27/92, 93. 

The scholars of the Standing Committee said:  

It is not permissible to bow when greeting or to take off
one’s shoes for someone. 

And they said: 

It is not permissible to bow in greeting to a Muslim or to a
kaafir, not with the upper part of the body or with the head, because bowing
is an act of worship and worship can only be done for Allaah alone. 

Shaykh ‘Abd al-‘Azeez ibn Baaz, Shaykh ‘Abd al-Razzaaq
‘Afeefi, Shaykh ‘Abd-Allaah ibn Ghadyaan, Shaykh ‘Abd-Allaah ibn Qa’ood. 

Fataawa al-Lajnah al-Daa’imah,
1/233, 234 

And Allaah knows best.