Rashi on Genesis 20:6/רש"י על בראשית כ׳:ו׳

1'ידעתי כי בתם לבבך וגו I KNOW THAT IN THE INTEGRITY OF THY HEART etc. — It is true that at first you had no intention of sinning, but you cannot claim innocency of hands (Genesis Rabbah 52:6) —

2because לא נתתיך I PERMITTED THEE NOT — It was not of your own will that you did not touch her, but it was “I” who withheld you from sinning, and “I” did not permit you the possibility to touch her (Genesis Rabbah 52:7). Similar examples of נתן in sense of permitting are, (31:7) “God permitted him not (לא נתנו)” and (Judges 15:1) “But her father did not permit him (ולא נתנו) to go in”.