The (changing) of the saakinah and tanween is defined in applied tajweed as: The changing of noon saakinah or the tanween into a , when followed by a with the observance of a lengthened ghunnah on the letter .
If the letter occurs immediately after a saakinah in the same word, or between two words (meaning the saakinah or the tanween would be at the end of word, and the the first letter of the next word), it is then required that the reader changes the saakinah or tanween into a hidden , with a ghunnah present. The saakinah is changed into a meem in pronunciation, not in the written word. You may note that most copies of the Qur’an have a very small meem written over or under the noon in this case, or the second line of a fat-h or kasrah tanween or dhammah of the tanween is replaced by a small meem. The little in this case has a tail on the end of it.
The hidden, not by leaving a small space between the lips, as some modern scholars have said, but by closing the lips and holding the for the length of the ghunnah, then opening them with the . This is the correct way of “hiding” the as written in the books of the old scholars, and as passed down in applied recitation by chains of transmission that go back to the Prophet Mohammed, .
Examples of the :
In this first example above, the saakinah is the last letter of the next to the last word of the written part of the aayah. The next word, starts with the letter . The is then changed in pronunciation to a , and this is held with a ghunnah, then the lips are separated pronouncing the letter .
In this example above, the saakinah is in the middle of the word and followed by the letter . The saakinah is changed into a just as in the previous example.
These two different aayaat are examples of the tanween being followed by the letter . The , or changing of the saakinah of the tanween into a , is done in the same way as the other examples. The little can be seen written over all of these examples. The little takes the place of the second dhammah, fat-h, or kasrah of the tanween.