A bad beginning makes a bad ending.

[κακῆς <ἀπ'> ἀρχῆς γίγνεται τέλος κακόν]

Euripides (485?-406? BC) Greek tragic dramatist

Æolus [Αἴολος], frag. 32 (TGF)
    (Source)

Nauck frag. 32. (Source (Greek)). Alternate translation:

A bad ending comes from a bad beginning.
[tr. Collard & Cropp (2008)]