- know smb. as one knows his ten fingers
- (know smb. (или smth.) as one knows his ten fingers (тж. know smb. или smth. like the back или palm of one's hand, уст. as well as a beggar knows his dish))прекрасно знать кого-л. (или что-л.); ≈ знать кого-л. (или что-л.) как свои пять пальцев
I know thou knowest every place by the river's side as well as... the beggar knows his dish. (W. Scott, ‘The Fortunes of Nigel’, ch. XXI) — Ты, я знаю, изучил все места на Темзе... как нищий свою суму.
Martin knows that place like the palm of his hand. (C. P. Snow, ‘The Affair’, ch. 11) — Мартин знает колледж как свои пять пальцев.
He knew his assets and his liabilities, as he knew his ten fingers. (Th. Dreiser, ‘The Financier’, ch. XXX) — Он прекрасно знал состояние своего актива и пассива.
I've lived in New York all my life, and I know Central Park like the back of my hand. (J. Salinger, ‘The Catcher in the Rye’, ch. XX) — Всю жизнь я прожил в Нью-Йорке и знаю Центральный парк вдоль и поперек.
Большой англо-русский фразеологический словарь. - М.: «Русский язык-Медиа».. 2006.