condition of vowel elongation (شَرْطُ الْمَدّ)
علوم القرآن
التعريف :
What is essential for the elongation of any of the three long vowels, which are the ā provided that it is preceded by a consonant with a short ‘a’, the ī preceded by a consonant with a short ‘i’, and the ū preceded by a consonant with a short ‘u’. An example showing all three cases is the word nūḥīhā (11: 49).