Hadith 745
Abu Juhaifah Wahb bin 'Abdullah (May Allah be pleased with him) reported:
عن أبى جحيفة وهب بن عبد الله رضى الله عنه قال: قال رسول الله صلى الله عليه وسلم: " لا آكل متكئاً" .((رواه البخارى))
Messenger of Allah (ﷺ) said, "I do not eat reclining (against a pillow)." [Al-Bukhari].
In plain words
He said he did not eat reclining back against a cushion. Sitting upright keeps a person mindful that food is a gift received with gratitude, not an indulgence to sink into.
Reference : Riyad as-Salihin 745 In-book reference : Book 2, Hadith 19