Exodus 23:19 "You shall not boil a kid in milk of its mother"

This Negative Mitzvah forbids us to cook milk and meat together.

All kosher kitchens should have separate counters, dishes, pots and silverware for meat and milk, in order not to mix the two together.

The verse from which this Negative Mitzvah is learned is repeated three times in the Torah and each time refers to a specific instance of using meat and milk together, (see Negative Mitzvah 187).