Rachel Aaron said this quote

First rule of thievery,' Eli said, grinning, 'only run if you're not coming back.' (...) 'First rule of thievery, never use the same entrance twice.' Miranda rolled her eyes. 'How many 'first rules' of thievery do you have?' 'When one mistake can mean your head on a pike, every rule's a first rule,' Eli said cheerfully.