Rashi on Genesis 3:3/רש"י על בראשית ג׳:ג׳

1ולא תגעו בו NEITHER SHALL YE TOUCH IT — She added to God’s command (which did not forbid touching the tree, but only eating of its fruit) therefore she was led to diminish from it. It is to this that the text refers (Proverbs 30:6): “Add thou not unto His words” (Genesis Rabbah 19:3).