Article — Wouters, Manual of Moral Theology
Article IV. The Time of Restitution
I. Restitution is to be made as soon as it can morally be made. He who cannot restore the entire damage should restore a part, if he can, and should strive according to his powers that he may be able to restore the remaining part. Delay of restitution, if there is question of a grave thing, is a grave sin from its genus, that is, he sins gravely who postpones the restitution of a grave thing for a long time, and he sins lightly who postpones it for a short time, unless grave damage to the owner would follow from the short delay (St. Alphonsus, III, 676, 679; Praxis confessarii, n. 43). A delay, for example, of three weeks is certainly brief (St. Alphonsus, loc. cit.).
II. He who has delayed restitution (or payment) is held to repair the emergent damage and ceasing profit which have followed from the delay and were foreseen at least confusedly, as follows:
He is held if he delayed without a legitimate cause, because by illegitimately delaying he placed or continued an unjust cause of damages.
He is not held if he delayed from a just cause, with the exception, more probably, of a debtor from delict; because although in the case the delay is not the unjust cause of damages, nevertheless the unjust cause was and remains the delict itself (St. Alphonsus, III, 680, 703, doubt 2).
Corollary. A dying person who is held to restitution (or payment) must be treated in this way:
If the dying person is in good faith, he must be warned, unless there is no time for warning, or it is feared that the warning will not be useful.
If the dying person was not in good faith, or has been deprived of it by the warning, let him wisely be induced to fulfill the obligation, and indeed immediately, if this can conveniently be done.
If the obligation cannot conveniently be fulfilled immediately, then:
a) If the obligation is public, let the dying person take care that it be fulfilled by the heirs, for example by handing over to the creditor a private written instrument completed in legitimate form.
b) If the obligation is hidden, let the sick person either hand over the sum owed to a prudent man, who may remit it to the creditor; or let him bequeath it to the creditor in his testament, if this can be done under some plausible pretext.