Khawāt b. Jubayr – Allāh be pleased with him – said:

Sleeping in the first part of the day is ignorance, and in the middle of the day [good] character, and in the last part of the day stupidity.

Al-Bukhārī, Al-Adab Al-Mufrad. Shaykh Al-Albānī graded its chain of transmission ṣaḥīḥ. See Ṣaḥīḥ Al-Adab Al-Mufrad hadith #947.