Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
Qurʾān Bukhārī Muslim Nasāʾī Abū Dāwūd Tirmidhī Ibn Mājah Mālik Aḥmad Dārimī Ḥākim Ibn Ḥibbān Ṭabarānī Nasāʾī's Kubrá Bayhaqī al-Luʾluʾ wa-al-Marjān Ibn Rajab's Fifty Riyāḍ al-Ṣāliḥīn Aḥmad's Zuhd Suyūṭī
quran:23:9 –

And they who carefully maintain their prayers -  

And who are watchful of their prayers (may be read as plural, salawātihim, ‘their prayers’, or singular, salātihim, ‘their prayer’) observing them at their appointed times.
القرآن:٢٣:٩ –

وَالَّذِينَ هُمْ عَلَىٰ صَلَوَاتِهِمْ يُحَافِظُونَ  

{والذين هم على صلواتهم} جمعاً ومفرداً {يحافظون} يقيمونها في أوقاتها.

See similar narrations below:

Collected by Qurʾān
quran:70:34 –

And those who ˹carefully˺ maintain their prayer:  

and who preserve their prayers, by observing them in their appointed times.
القرآن:٧٠:٣٤ –

وَالَّذِينَ هُمْ عَلَىٰ صَلَاتِهِمْ يُحَافِظُونَ  

{والذين هم على صلاتهم يحافظون} بأدائها في أوقاتها.