Jerusalem Talmud, Berachot 7:5

Rabbi Ba the son of Rav Hiyya bar Abba teaches: If one ate while walking, one must stand and bless. If one ate standing, one must sit and bless. If one ate sitting, one must recline [formally] and bless. If one ate reclining, one must enwrap himself and bless. And if one did this, one is like the angels who serve God. [translation by Hazon]