Mishneh Torah — Negative Mitzvot מצוות לא תעשה, Chapter 99
The full Hebrew text of Mishneh Torah, Negative Mitzvot, Chapter 99, with English translation by Maimonides (Rambam).
שלא להקריב תפל, שנאמר "ולא תשבית מלח ברית אלוהיך" (ויקרא ב,יג).
Not to offer a sacrifice which is unsalted, as [Leviticus 2:13] states: "Do not omit the salt of God's covenant."