And bad luck reveals those who are not real friends, but just happen to be so because of utility.

[ἡ δ᾽ ἀτυχία δηλοῖ τοὺς μὴ ὄντως [20] ὄντας φίλους, ἀλλὰ διὰ τὸ χρήσιμον τυχόντας.]

Aristotle (384-322 BC) Greek philosopher

Eudemian Ethics [Ἠθικὰ Εὐδήμεια], Book 7, ch. 2 / 1238a.19-20 [tr. Reeve (2021)]
    (Source)

(Source (Greek)). Alternate translations:

Misfortune shows those who are not really friends, but friends only for some accidental utility.
[tr. Solomon (1915)]

Misfortune shows those who are not friends really but only because of some casual utility.
[tr. Rackham (1981)]

But misfortune shows those who are friends not really but because of chance utility.
[tr. Simpson (2013)]