This is the last section in the mudood (lengthenings) category.  In it we discuss which medd (lengthening) we choose when two different types of lengthenings share the same medd letter. 

We learned that the Secondary Lengthening 
() is due to two causes: 

1. The hamzah 

  2. The Sukoon.  

The lengthening due a hamzah are three kinds: The Exchange Lengthening (), The Required Joined Lengthening (), and The Allowed Separated Lengthening  (). 

  The medd due to a sukoon is of two kinds: The Presented Sukoon Lengthening
() and the Compulsory Lengthening ().  

The leen is considered a branch of the presented sukoon lengthening .  These lengthenings have various degrees of strength and weakness.  The strongest is the compulsory lengthening (), the second strongest is the required joined lengthening 
(), the next the presented sukoon lengthening (), then separated allowed lengthening 
(), and the weakest the exchange lengthening ().  

The following lines of poetry written by  ِAsh-Sheikh Ibrahim Ali Shahaatah reinforce the ranking of the various secondary lengthenings:

Translated:  
The stronger of the lengthenings is compulsory then that which is joined,
Then presented and that which is separated, then exchange. 

The Rule of the Stronger of the Two Causes for a Lengthening

If two reasons for lengthening are present in one medd letter, there must be one stronger than the other.  In this case the weak medd is left, and we use the stronger of the two.  The following lines of poetry also written by Sheikh Ibrahim Ali Shahaatah exemplify this:

Translated: 
Two causes for lengthening if they are found
Then verily the stronger of the two causes performs.

Examples:

Example 1:

In this word, there is a hamzah before the medd letter (), this is therefore an exchange lengthening ().  This same medd letter is followed by a shaddah, meaning a sukoon, so we also have the compulsory lengthening ().  With the knowledge that the stronger of these two medd is the , we use that medd and do not use the exchange lengthening ().  This medd is lengthened six counts, that of the compulsory lengthening ().

Example 2:

In this example a hamzah precedes a medd letter (), so there is an exchange lengthening (). The same medd letter is followed by a hamzah in the same word, so there is also a required joined lengthening ().  Both of these medd share the same medd letter, the alif, and since the stronger of the two lengthenings is the required joined lengthening, we apply that lengthening and not the exchange lengthening. This medd is therefore lengthened four or five vowel counts.  When stopping on this same medd, or any word that has a hamzah at the end of it after a medd letter, we have three different possibilities:
If the reader is reading the required joined lengthening,,four counts, he can stop on this medd four. Four counts would lead to a medd with two causes, which would be, the required joined lengthening 
()and the presented sukoon lengthening ().
Stopping on this word with six vowel counts would be allowed only if all of were being lengthened six vowel counts and then only the presented sukoon lengthening  would be the reason for this lengthening 
If the reader is reading the required joined lengthening () with five vowel counts, he can stop on this with five vowel counts. Stopping on five vowel counts would be employing only the required joined lengthening ().  It is forbidden to stop on this word using the present sukoon lengthening 
() with two vowel counts.  This is due to the rule of the stronger of the two lengthenings 
(), and since the required joined lengthening is stronger than the the presented sukoon lengthening, the lesser count on the presented sukoon lengthening cannot be used.

Example 3:In the above example, the hamzah precedes a medd letter, indicating an exchange lengthening ().  This medd is at the end of the word, and the first letter of the next word is a hamzah, so the allowed separated lengthening 
() is also using this same medd letter, which is an alif.
In this case, when continuing reading, and the allowed separated lengthening 
() is employed, so we lengthen this medd 4, or 5 counts (by the way we read).  There is a way of reading by Hafs ‘an ‘Aasim, not the way of Ash-Shatibiyyah that lengthens the allowed separated lengthening two vowel counts.  If is lengthened two vowel counts, then the medd is shared, and both the allowed separated lengthening and the exchange lengthening are considered to be in use at the same time. When stopping on the first word only the exchange lengthening () is used, since the hamzah that begins the second word is not being read, and there is therefore no allowed separate lengthening 
() is used. 

Test your ability to find two lengthenings sharing a medd letter:

Find in the following aayaat words that have two different lengthenings sharing a medd letter, find the circumstances for the two lengthenings sharing the medd letter (i.e. only when stopping, only when continuing) and find the stronger of the two, and the length of the medd that is employed.

1.

2.

3. Are there two lengthenings sharing a medd letter when stopping on the word ?  Why or why not?