But, of all motives, none is better adapted to secure influence and hold it fast than love; nothing is more foreign to that end than fear. […] For fear is but a poor safeguard of lasting power; while affection, on the other hand, may be trusted to keep it safe for ever.

[Omnium autem rerum nec aptius est quicquam ad opes tuendas ac tenendas quam diligi nec alienius quam timeri. … Malus enim est custos diuturnitatis metus contraque benivolentia fidelis vel ad perpetuitatem.]

Marcus Tullius Cicero (106-43 BC) Roman orator, statesman, philosopher

De Officiis [On Duties; On Moral Duty; The Offices], Book 2, ch. 7 (2.7) / sec. 23 (44 BC) [tr. Miller (1913)]
    (Source)

Discussing the fate of tyrants such as Julius Caesar. Original Latin. Alternate translations:

Now of all those methods, which tend to the advancement and maintenance of our interest, there is none more proper and convenient than love, and none more improper and inconvenient than fear. [...] For obedience, proceeding from fear, cannot possibly be lasting; whereas that which is the effect of love will be faithful for ever.
[tr. Cockman (1699)]

Of all means there is none better fitted for supporting and retaining our influence than to be loved; or more foreign to it, than to be feared. [...] Fear is a false and short-lived security, but the love of men is faithful and lasting.
[tr. McCartney (1798)]

Now, of all things there is none more adapted for supporting and retaining our influence than to be loved, nor more prejudicial than to be feared. [...] For fear is but a bad guardian to permanency, whereas affection is faithful even to perpetuity.
[tr. Edmonds (1865)]

But of all things nothing tends so much to the guarding and keeping of resources as to be the object of affection; nor is anything more foreign to that end than to be the object of fear. [...] For fear is but a poor guardian for permanent possession, and, on the other hand, good will is faithful so long as there can be need of its loyalty.
[tr. Peabody (1883)]

Of all the means of maintaining power, love is the best, the worst fear. [...] Fear is a poor guardian of lasting power; love will keep it safe for ever.
[tr. Gardiner (1899)]

However, among all qualities there is no more appropriate way to preserve and defend one's resources than to be well-liked, nothing less appropriate than to be feared. [...] To arouse fear in others is a bad guarantee of longevity, while on the other hand good will is faithful unto eternity.
[tr. Edinger (1974)]