Sénèque
It is not that we have little time, but that we waste much.
Misconceptions
"To err is human, to persist is diabolical" is a saying of Seneca.
It is not found in his surviving works, and the word "diabolical" is Christian. The idea appears in Cicero (Philippics XII, 5: anyone can err, only a fool persists in error) and the phrasing is close to a sermon of Augustine (Sermon 164). None of these texts is in our corpus yet.
Seneca corresponded with Saint Paul.
A correspondence of fourteen letters between Seneca and Paul does exist, but it is a forgery written in the 4th century (Saint Jerome knows it around 392). Neither style nor content is Seneca's or Paul's. Nothing proves they ever met.
Seneca preached poverty but lived in luxury: a hypocrite.
He was indeed immensely rich, and his enemies held it against him in his lifetime (the historian Tacitus reports an accusation from the year 58). He answers himself: he does not claim to despise wealth to the point of refusing it, only not to depend on it; the wise man "does not love riches, but he prefers to have them". And he admits: "I am not a wise man." The debate on his consistency has gone on since antiquity.
For a Stoic, the wise man does not feel pain.
Seneca says so himself: "I do not say that he does not feel them, but he conquers them". He also allows involuntary "first movements" (turning pale, shivering, being shaken), which affect even the wise man: what he rejects is giving in to them.