From the scholia to the famous opening line of Homer, Iliad: "sing, goddess, of the wrath of Peleus' son Achilles" (web address 1 below).
There, as elsewhere, the Homeric form of this imperative is a)/eide. The Attic contracted form is ai)=de. In Attic tragedy, uncontracted forms of the verb occur (poetic archaism) as well as contracted forms.