Mishneh Torah — Positive Mitzvot מצוות עשה, Chapter 19
The full Hebrew text of Mishneh Torah, Positive Mitzvot, Chapter 19, with English translation by Maimonides (Rambam).
לְבָרַךְ אַחַר הַמָּזוֹן, שֶׁנֶּאֱמָר: "וְאָכַלְתָּ וְשָׂבָעְתָּ וּבֵרַכְתָּ אֶת יְיָ אֱלֹהֶיךָ" (דברים ח, י).
To bless [God] after eating, as [Deuteronomy 8:10] states: "[After] you eat and are satisfied, you shall bless God, your Lord."