Bukhari

Hadith Commentary:
1.
It is narrated from Qutbah bin Malik radi Allahu anhu, who said that he heard the Messenger of Allah sallallahu alayhi wa sallam reciting Surah Qaf in the Fajr prayer. When he reached (لَّهَا طَلْعٌ نَّضِيدٌ), he elongated the recitation of (نَّضِيدٌ).
(al-Sunan al-Kubra lil-Bayhaqi: 2/54 and Fath al-Bari: 9/114)

2.
There are two types of madd (elongation):
➊.
Madd asli: The letters of madd are recited with elongation.
➋.
Madd ghayr asli:
When a letter of madd is followed by a hamzah, there are two cases:
➊.
If the hamzah comes after the letter of madd within the same word, it is called madd muttasil, such as (مَآءٍ) and (سوّء).
➋.
If the hamzah comes after the letter of madd in a different word, it is called madd munfasil, such as (إِلَّا أَنفُسَهُمْ).
Madd ghayr asli should be recited with ample elongation.
The Messenger of Allah sallallahu alayhi wa sallam would also elongate the letters of madd in his recitation.
(Fath al-Bari: 9/114)

1465. Commentary: That is, the words in which there is *madd* (elongation), they would recite with elongation, and those in which there is *leen* (softness), they would recite with softness. The purpose is that they would recite with the well-known Arabic melody (lahan).

1015. Commentary: This does not mean that he would elongate unnecessarily, rather, he would recite with elongation (madd) only on those letters where it is prescribed. By elongating the letters of madd, tranquility and composure are produced in the recitation, which is called tartil, and this is necessary. This provides an opportunity to reflect and ponder upon the Noble Qur’an. Reciting hastily, in such a way that nothing is understood except for “ya‘lamun” and “ta‘lamun,” is a blameworthy form of recitation.

Benefits and Issues:
The meaning is that those words which can be recited with elongation, they used to recite them by elongating and stretching them. For example, when an alif is joined with a letter, or when a sakin (quiescent) waw comes after a dammah (pesh), or when a sakin ya comes after a kasrah (zair), then these letters will be recited relatively longer.

It is not correct to stretch and elongate a letter that only has a zair, zabbar, or pesh (kasrah, fathah, or dammah) when there is no alif, waw, or ya sakin present after it. For example, in:
﴿إِنَّا أَعْطَيْنَاكَ الْكَوْثَرَ﴾, reciting إِنَّ or أَعْطَیْنَ with elongation is incorrect. Similarly, reciting ﴿فَصَلِّ لِرَبِّكَ وَانْحَرْ﴾ as فَصَلِّیْ لِرَبِّکَا is not correct.