From That the True Dhamma Might Last a Long Time: Readings Selected by King Asoka, translated by Thanissaro Bhikkhu.
"Bhikkhus, whatever I have not objected to, saying, 'This is not allowable,' if it fits in with what is not allowable, if it goes against what is allowable, this is not allowable for you.
"Whatever I have not objected to, saying, 'This is not allowable,' if it fits in with what is allowable, if it goes against what is not allowable, this is allowable for you.
"And whatever I have not permitted, saying, 'This is allowable,' if it fits in with what is not allowable, if it goes against what is allowable, this is not allowable for you.
"And whatever I have not permitted, saying, 'This is allowable,' if it fits in with what is allowable, if it goes against what is not allowable, this is allowable for you."