Seneca, De Beneficiis 2.2
When the spirit is worn out and begins to hate a benefit while it waits for it, is it possible to still be grateful? Just as it is the most bitter cruelty which makes a punishment last longer and that killing quickly is a kind of mercy since torment supplies its own final end and the time which comes before death is the greatest period of suffering, so too gratitude for a gift will be greater the shorter the duration of suspense.
For the expectation of good things is upsetting too and since most gifts bring relief from some kind of thing, if anyone allows someone else to be tortured for a while when he was able to free him of burden or if he is slow to rejoice, he has added a punitive slap to his good deed. All generosity should move quickly—someone who acts quickly is someone who acts voluntarily. If someone drags his feet day to day, he does not act according to his spirit. He has thus lost two precious things: time and the demonstration of willing friendship. Consenting slowly is an indication of someone who is unwilling.”
Ubi in taedium adductus animus incipit beneficium odisse, dum expectat, potest ob id gratus esse? Quemadmodum acerbissima crudelitas est, quae trahit poenam, et misericordiae genus est cito occidere, quia tormentum ultimum finem sui secum adfert, quod antecedit tempus, maxima venturi supplicii pars est, ita maior est muneris gratia, quo minus diu pependit. Est enim etiam bonarum rerum sollicita expectatio, et cum plurima beneficia remedium alicuius rei adferant, qui aut diutius torqueri patitur, quem protinus potest liberare, aut tardius gaudere, beneficio suo manus adfert. Omnis benignitas properat, et proprium est libenter facientis cito facere; qui tarde et diem de die extrahens profuit, non ex animo fecit. Ita duas res maximas perdidit, et tempus et argumentum amicae voluntatis; tarde velle nolentis est.