“Will you walk into my parlour?” said a spider to a fly:
“‘Tis the prettiest little parlour that ever you did spy.”

Mary Howitt (1799-1888) English poet

Poem (1828), “The Spider and the Fly,” st. 1, The New Year’s Gift and Juvenile Souvenir [ed. Mrs. Alaric Watts]
    (Source)

Variant: “Step into my parlor, said the spider to the fly …”

The poem has been parodied frequently, including by Lewis Carroll's "Mock Turtle's Song." More information about this poem here.