Undesirability of Eating in a Reclining Posture Riyad as-Salihin 746
Arabic hadith text
وعن أنس رضى الله عنه قال: رأيت رسول الله صلى الله عليه وسلم جالساً مقعياً يأكل تمراً. ((رواه مسلم))
Translation
Anas (May Allah be pleased with him) reported
I saw Messenger of Allah (ﷺ) eating some dates while sitting on his buttocks, with his legs raised.[Muslim].