As reported in the books of ḥadīth, the Prophet (peace and blessings be upon him) would at times repeat a single verse during the night prayer to such an extent that it was as though he spent the night with it until morning. (See: al-Nasāʾī, 1010; Ibn Mājah, 1350; Musnad, 21538)
Accordingly, we understand first and foremost that this is permissible. The repetition of a verse—when it arises from khushūʿ, from the effect of the verse upon the individual, or from reflecting upon it—is good and in accordance with the Sunnah. However, when it occurs due to reasons not in harmony with the spirit of the prayer, such as waswasa or ostentation, it is a behavior that should not be practiced.
This is the case when praying individually and in supererogatory prayers. As for the imam repeating certain verses during congregational prayer, greater caution is required here, especially in obligatory and wājib prayers. Nevertheless, there is no objection to the imam repeating certain verses, whether due to the effect of the verse upon himself, for the purpose of reflecting upon it and prompting reflection in others or in order to draw the congregation’s attention to the meaning of the verse—provided that this does not lead to confusion among the congregation or cause them to become weary. On this basis, if it is to be done, it should not be repeated more than one or two times, and it should not be done very frequently.