A direct quote from Horace about validation and the futility of seeking external praise can be found in his Epistles, particularly Epistle I.1. Here’s one of the most well-known lines, in Latin and English:
“Quid enim? Concurritur: horae
momento cita mors venit aut victoria laeta.”
“What then? They rush into the fray: in a moment, swift death may come—or a joyful victory.”
But more relevant to your question about validation and praise, this is the most pointed quote:
“Nil admirari prope res est una, Numici,
solaque quae possit facere et servare beatum.”
“To admire nothing—that is, Numicius, almost the one and only thing that can make and keep a man happy.”
This is from Epistles I.6. The idea here is that freedom from needing to admire—or be admired—is the key to peace. In modern terms: validation is a trap.
Or this one from Epistles I.1 again:
“Laudatur ab his, culpatur ab illis.”
“Praised by these, blamed by those.”
Here, Horace mocks the inconsistency of public opinion. The wise person, he implies, should not build their self-worth on the shifting sands of others’ praise or blame.