In Book 10 of Diogenes Laertius

Various sayings concerning the Wise Man. Wisdom does not so much prevent natural feelings from emerging entirely. Instead, when they break out spontaneously, wisdom diverts the mind toward honorable thoughts. This makes these outbursts both less frequent and less severe. Epicurus certainly taught this by his own example. Regarding those pains so great that nothing could be added to their magnitude, he said: The joy of my soul, which I drew from the memory of our reasonings and discoveries, compensated for all these things.

From here, we may appropriately address another difficulty raised by Cicero and Plutarch. Seneca writes on this matter in this way:
Letter 92.

Furthermore, he asks, does it not seem equally incredible that someone placed in the greatest tortures should say, I am blessed? And yet this voice was heard in the very workshop of pleasure. I am spending my most blessed and final day, said Epicurus. At that moment, he was tortured on one side by the difficulty of urination and on the other by the incurable pain of a diseased stomach. In this passage, the phrase in the workshop of pleasure serves as a warning. Just as the pleasure pursued by Epicurus suffered from a malicious interpretation, so too does his claim that the Wise Man is blessed in the midst of torments. It seems like an invitation to spiteful interpretation when he judged that the Wise Man, even in the Bull of Phalaris A hollow bronze statue used as a torture device: the victim was locked inside and roasted over a fire while their screams sounded like the bellowing of a bull., would say: How sweet this is! How I do not care for this! How I consider this as nothing!

These words gave an opportunity for mockery, not only to Cicero but also to Lactantius, whose words are these:
Book 3, chapter 26.

Epicurus says much more boldly: The Wise Man, he says, is always blessed, and even when enclosed in the bull of Phalaris, he will utter this voice: It is sweet, and I do not care. Who would not laugh at him? Especially because a man of pleasure has taken upon himself the mask of a brave man, and indeed beyond all measure. For it is not possible for anyone to consider the tortures of the body as pleasures. It is enough to fulfill the duty of virtue by enduring and sustaining them.

Indeed, Epicurus truly thought nothing else than what is argued in these last words by Lactantius, and Cicero thinks no differently. Cicero says: I do not attribute such great power to Wisdom against pain. It is enough to be brave in performing one's duty; I do not demand that he also rejoices. For pain is without doubt a sad thing, harsh, bitter, and an enemy to nature, difficult to suffer and tolerate. I say that Epicurus thought and said nothing else. This can be understood from Seneca himself. Although Seneca also has this: I could answer that Epicurus says the Wise Man, if he is burned in the bull of Phalaris, will exclaim: It is sweet, and it pertains nothing to me. Yet, these are the words he adds later: I will give you a division of goods in Epicurus very similar to our own. For in his view, some things are those he would prefer to happen to him, such as bodily rest free from all discomfort and a relaxation of the mind rejoicing in the contemplation of its own goods. Others are things that, although he would not wish them to happen, he nonetheless praises and approves. Such is the endurance of ill health and the most serious pains I mentioned a moment ago, which Epicurus experienced on that final and most

fortunate day of his. For he says he tolerates the torments of the bladder and an ulcerated stomach, which could not receive any further increase in pain. He says that day was nonetheless blessed for him. No one can spend a blessed day unless they possess the "highest good" original: "summum bonum".
On page 78.

Therefore, in the house of Epicurus, there are these goods that you would prefer not to experience; but because circumstances brought them, they must be embraced, praised, and made equal to the highest goods. It cannot be said that this good is not equal to the greatest, for it placed the closing seal on a blessed life, for which Epicurus gave thanks with his final voice.

This was partly mentioned elsewhere. I pass over what Seneca also said after mentioning what Attalus the Stoic used to say:
Letter 67.

I prefer that Fortune holds me in her military camp rather than in her delights. I am tortured, but bravely; it is well. I am killed, but bravely; it is well. Then, Seneca adds in this manner: Listen to Epicurus; he will say, it is even sweet. I will never apply such a soft name to so honorable and severe a matter. I am burned; but I am unconquered. Why should it not be desirable, not that the fire burns me, but that it does not defeat me? Nothing is more excellent than virtue, nothing more beautiful; whatever is done under her command is both good and desirable.

However it may be, and to make it brief: this matter should not seem incredible to us especially. Among us there exist so many examples of the most blessed Martyrs. Their constancy in the midst of torments was incomparably more cheerful than that of any Anaxarchus, Zeno, or other ethnic Non-Christian or pagan. Wise Men. It is specifically sung of the holy Protomartyr Saint Stephen, the first Christian martyr. that the stones of the torrent were sweet to him.

PAGE 75 Verse 1. Only the wise man will show gratitude. original: "Μόνον τε χάριν ἕξειν τὸν σοφόν" For the last words of this saying, even when dead original: "ἢ καὶ ἀποθανόντα", I have substituted through every path original: "διὰ πᾶν ὁδὸν", from which nothing can be drawn that makes sense. It is a faint trail for a correction; but at least the step is placed on the fact that Epicurus held the memory of even dead friends as very dear, and so he judged it should be cherished. The matter is clear from his own Will. In it, he commanded that the memory of the deceased Metrodorus and Polyaenus be celebrated every year, just as he had celebrated it while alive. He ordered that the care of the children of both men be maintained, just as he himself had maintained it. Furthermore, Epicurus expresses the constancy by which true friendship is proven: in presence, in absence, in death itself, and thus at absolutely all times. This certainly encompasses those two times in which the quality of friends is tested: namely, the prosperous fortune of one and the adverse fortune of the other. For it is very common that either someone becomes more burdened with wealth and despises an old friend, or another falls into calamity and is deserted by him. Cicero rightly throws that line of Ennius against such people:
Ibid.

A sure friend is seen in an unsure matter.

Concerning this fake kind of friends, that line of Euripides can also be used: