Mishneh Torah — Positive Mitzvot מצוות עשה, Chapter 3
The full Hebrew text of Mishneh Torah, Positive Mitzvot, Chapter 3, with English translation by Maimonides (Rambam).
לְאָהֳבוֹ, שֶׁנֶּאֱמָר: "וְאָהַבְתָּ, אֵת ה' אֱלֹהֶיךָ" (דברים ו ה, יא א).
To love Him, as [Deuteronomy 6:5] states: "And you shall love God, your Lord."