Tafsir of Al-Insan 76:25

"And mention the name of your Lord in the morning and the evening," meaning: persist in His remembrance—glory be to Him—at all times. Or, persist in the Dawn (Fajr) and Noon (Dhuhr) prayers, for the term 'evening' (al-asil) may be applied to the time from the passing of the sun's meridian (post-noon) until sunset, thus encompassing both of them.