In The Waste Land lines 25 through 30 are derived from an earlier, unpublished work of Eliot's entitled The Death of Saint Narcissus

Compare The Waste Land

• 25)  There is shadow under this red rock,
• 26)  (Come in under the shadow of this red rock),
• 27)  And I will show you something different from either
• 28)  Your shadow at morning striding behind you
• 29)  Or your shadow at evening rising to meet you;
• 30)  I will show you fear in a handful of dust.

• Come under the shadow of this grey rock
• Come in under the shadow of this grey rock
• And I will show you a shadow different from either
• Your shadow sprawling over the sand at daybreak, or
• Your shadow leaping behind the fire against the red rock:
• I will show you his bloody cloth and limbs
• And the grey shadow on his lips.

The draft versions of The Death of Saint Narcissus are available in the book The Waste Land - A Facsimile and Transcript of the Original Drafts