Velarization (Heaviness) and Lightness 
Part 4
Letters that are Lightened Sometimes and are Made Heavy Other Times
The Four Cases in Which the 
Has Tarqeeq
1. If
the has a
kasrah, as in :
2. If
the is
saakinah, and a kasrah precedes it, such as:
Click here to listen
3. If
the is
saakinah, and the letter before it is saakin, and the letter before that has a
kasrah. This would occur when stopping, as in the example:
4. If
it is saakinah, and a 
saakinah
precedes it. The in this case
has tarqeeq no matter what kind of vowel precedes the saakinah.
This is exemplified in the following words:
(when
stopping on these words).
The Cases Where Both Tafkheem and Tarqeeq are Allowed of the
1. If the is
saakinah, and it is preceded by a kasrah, and it is followed by a letter of 
group, and
this letter has a kasrah. There is only one example of this in the Holy Qur’an, and
that is the word 
in verse 63 of surah
Ash-Shuraraa’. The two different ways of reading the apply
when continuing the reading, not when stopping. When stopping on the word the
has
tafkheem, according to the eighth case in which the has
tafkheem.
2. If the is
saakinah and it is preceded by a saakin letter, which is preceded by a kasrah,
and the saakin letter which precedes the , is a
letter of group.
There are two words in the Qur’an that have these circumstances when
stopping on them. They are the words
which
is in verse 12 of surah Saba’ and the word,
which
is in verse 21, and 99, of surah Yusef, and verse 51 of Az-Zukhruf. These two
words can be read with tafkheem or tarqeeq of the when
stopping on them. When reading these words in continuum with that which
comes after, the rule of the letter depends on
the vowel on the ; if there
is a fat-h or dhammah, the is read
with tafkheem, if there is a kasrah, the is read
with tarqeeq.
The Letters that Always have Tarqeeq
The rest of the letters in 
group that
remain always have tarqeeq. These are all letters of except
the alif, the laam of the Glorious name of Allah, and the .