Mishneh Torah — Negative Mitzvot מצוות לא תעשה, Chapter 64
The full Hebrew text of Mishneh Torah, Negative Mitzvot, Chapter 64, with English translation by Maimonides (Rambam).
שלא לנסות את דבר ה', שנאמר "לֹא תְנַסּוּ אֶת ה' אֱלֹהֵיכֶם" (דברים ו, טז).
Not to test the promises of God, as [Deuteronomy 6:16] states: "Do not test God, your Lord."