Do not unto another that which you would not he should do unto you.

[Quod tibi fieri non vis, alteri ne feceris.]

Propertius (50–16 BC) Roman elegiac poet [Sextus Propertius]

(Misattributed)
    (Source)

This "negative" rendition of the Golden Rule is frequently included in Internet bulk lists of quotes by Propertius (e.g. 1, 2), but is not actually from his writings.

The misattribution seems to come from Alfred Henderson's seminal Latin Proverbs and Quotations (1869), which attributes the quote to "Prosp." -- probably Prosper of Aquitaine (c. AD 390–455), a follower of Augustine who wrote extensively, though Henderson includes no other quote by him. This was seemingly misread or misunderstood by later readers (or scrapers) as an attribution to "Prop." -- used by Henderson to refer to Propertius.