Khawwat ibn Jubayr said “Sleeping during the beginning of the day is stupidity. Sleeping during the middle of the day is upright character, and sleeping at the last part of it is imbecility.”
Reported by al-Bukhaari in Adabul Mufrad. Graded Saheeh by Albany rahimahullah
Ash-Shaykh Muhammad bin Saalih al-Uthaymeen rahimahullah clarifies that what is preferable for a person to busy himself after Fajr until sun rise is with the remembrance of Allah or with reciting the Quran due to the ayah:
وسبح بحمد ربك قبل طلوع الشمس
“And glorify the praises of your Lord before the rising of the sun”
However, the Shaykh went on to mention if the person is extremely tired or doesn’t find time to rest except during this timing, then there is no harm upon him in doing so.
AbdulFattaah Bin Uthman