Modulation and elongation of vowels in the Adhaan

It is not permissible
to sing the adhaan, but this is not like the prohibition of singing
itself; it varies between being makrooh or being haraam, unless the
meaning is altered, in which case it becomes haraam. 

    Zayn al-Deen al-‘Iraaqi said: 

It is mustahabb to elongate
the vowels slightly in the adhaan, but it is makrooh to elongate them
too much in the manner of singing, because it was narrated that a man
said to Ibn ‘Umar, “I love you for the sake of Allaah,” and he replied,
“I hate you for the sake of Allaah, for you overstep the mark in your
adhaan.” Hammaad said, he meant singing. 

     Wali al-Deen al-‘Iraaqi said: 

Al-Shaashi
said in al-Mu’tamad: the correct way is for the voice to have
a soft and sad tone, not harsh like the speech of the Bedouins or soft
like the voice of one who is dying… The author of al-Haawi said:
Overstepping the mark means speaking in an emphatic and exaggerated
manner. He said, it is makrooh to make the adhaan like singing because
it makes it incomprehensible, and because the salaf did not do that,
rather it is something that was innovated after their time.

(Tarh al-Tathreeb,
3/118-120) 

Ibn al-Haaj said: 

Chapter on the prohibition
of making the adhaan like singing 

One must be careful to
avoid giving a tune like singing to the adhaan, and one must also tell
others not to do things that they have innovated by making it resemble
singing, whereby it is given a joyful tune like singing until one cannot
tell what they are saying in the words of the adhaan, and it is just
voices going up and down. This is a repulsive recently-invented bid’ah
(innovation) which some governors introduced in a school that they had
built, then it spread from there. This adhaan is done in Syria at this
time, and it is a vile innovation, because the purpose of the adhaan
is to call people to prayer, so the words must be made understandable
to the listener – but in this adhaan nothing can be understood, because
the words have been changed into something that resembles singing. It
was narrated in the hadeeth that the Prophet
(peace and blessings of Allaah be upon him) said: “Whoever innovates
something in this matter of ours (i.e., Islam) that is not part of it,
will have it rejected.” Imaam Abu Taalib al-Makki (may Allaah have mercy
on him) said in his book: one of the things that they have innovated
is modulation (varying the tone) in the adhaan, which is a kind of exaggeration
and overstepping the mark. One of the muezzins said to Ibn ‘Umar, “I
love you for the sake of Allaah,” and he replied, “But I hate you for
the sake of Allaah.” He asked, “Why, O Abu ‘Abd al-Rahmaan?” He said,
“Because you exaggerate in your adhaan, and you accept payment for it.”
Abu Bakr al-Aajurri (may Allaah have mercy on him) used to say, I left
Baghdaad and I cannot stay there because of the innovations that they
have introduced into everything, even in Qur’aan recitation and the
adhaan – meaning that they accepted payment for it and they had introduced
modulation (varying the tone or pitch, like singing). (al-Madhkal
2/245, 246) 

4. It was said in al-Mudawwanah:
it is makrooh to sing in an emotional tone in the adhaan. And
it was said in al-Tiraaz that singing in an emotional tone means
making the voice go up and down, which stems from the loss of equilibrium
which happens when a person experiences extremes of happiness or grief;
it is a kind of confusion or panic. 

It was said in al-‘Atbiyah
that giving an emotional tone to the adhaan is munkar (to be denounced).
Ibn Habeeb said: (it is also makrooh) to give it a grieving tone without
singing. The letters should not be altered or sung. The Sunnah is to
enunciate it clearly in a loud voice. 

Ibn Farhoon said: singing
in en emotional tone means making short vowels long and long vowels
short. ‘Abd-Allaah ibn ‘Umar heard a man doing this in his adhaan, and
he said, “If ‘Umar were alive, he would break your jaw!” Ibn Maaji said,
Singing the adhaan in an emotional tone is makrooh, because it goes
against humility and dignity, and takes the pattern of singing. The
degree to which it is makrooh depends on the type, if it does not reach
the level of promiscuous singing; if it does reach that level, then
it is haraam. Ibn Habeeb made a connection between a sad tone and a
joyful tone, as narrated by Abu Muhammad. 

From this it may be
understood that it is mustahabb for the muezzin to have a pleasant and
loud voice, and for his voice to resonate. It is makrooh for him to
have a harsh and unpleasant voice, and to give the adhaan a joyful or
a sad tone; if that reaches extreme levels, then it is haraam. 

(Mawaahib al-Jaleel
by Hattaab, 1/437, 438) 

Shaykh Muhammad ibn Ibraaheem (may Allaah have mercy
on him) said: 

One should not elongate
excessively in the adhaan, and if doing so distorts the meaning, then
it invalidates the adhaan. If the elongated letters (huroof al-madd)
are made longer than necessary, this should not be done, and if regular
vowels are elongated in a manner that changes the meaning, this invalidates
the adhaan, otherwise it is makrooh. 

(Fataawa al-Shaykh
Muhammad ibn Ibraaheem, 2/125) 

Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him)
said: 

The mulahhan or the
one who introduces modulation into the adhaan is the one who gives the
adhaan in the manner of singing, as if he is singing the words of a
song. His adhaan is valid but it is makrooh. 

The malhoon is the
one who makes grammatical mistakes, i.e., he goes against the rules
of the Arabic language. But this falls into two categories, those which
invalidate the adhaan, which are those which alter the meaning, and
those with which the adhaan is still valid, but it is makrooh, which
do not alter the meaning. So if the muezzin says “Allaahu akbaar”,
the adhaan is not valid, because he is changing the meaning. Akbaar
is the plural of kabar, just as asbaab is the plural of
sabab. Kabar is a kind of drum  (Al-Sharh al-Mumti’,
2/62, 63) 

And Allaah knows best.