Tafsir of Al-Mu'minoon 23:9

"And those who are..."

It is also recited: "concerning their prayers" (‘alā ṣalawātihim).

If you ask: How is the mention of prayer repeated at the beginning and the end?

I say: They are two distinct mentions, so it is not a repetition. They were described first by khushū‘ (humility/reverence) in their prayer, and finally by muḥāfaẓah (diligence/guarding) over it. This means they do not neglect it, they perform it at its appointed times, they establish its pillars, and they commit themselves to caring for it and for everything required to perfect its qualities.

Furthermore, it was singular at the beginning to signify khushū‘ in the genus of prayer—whatever prayer it may be—and it was plural at the end to signify the diligence required for its various types: the five daily prayers, the witr, the established sunan accompanying each prayer, the Friday prayer, the two ‘Īds, the funeral prayer, the prayer for rain (istisqā’), the solar and lunar eclipse prayers, the ḍuḥā prayer, the tahajjud, the prayer of glorification (tasbīḥ), the prayer of need (ḥājah), and other supererogatory prayers.

"These are the inheritors, who will inherit Paradise; they will abide therein eternally."