The island of Manhattan derives its name from its earliest inhabitants, the Manhattan Indians.

10 seconds sound clip from the The Seven Year Itch (1952) movie soundboard.

You can hear this line at 00:02:26 in the Blu-ray version of the movie.

Quote context

[...]

- The island of Manhattan derives its name from its earliest inhabitants, the Manhattan Indians.

- They were a peaceful tribe - setting traps, fishing, hunting.

- And there was a custom among them: every July, when the heat and the humidity on the island became unbearable...

- They would send their wives and children away for the summer, up the river to the cooler highlands, or, if they could afford it, to the seashore.

- The husbands, of course, would remain behind on the steaming island to attend to business - setting traps, fishing and hunting.

- Actually, our story has nothing whatsoever to do with Indians. It plays 500 years later.

[...]