219:9 Even though there is no mourning on a holiday, we nevertheless comfort the bereaved. This is not considered mourning because the mourner isn’t doing anything. After the holiday, when seven days from the burial have been concluded, even though the week of observing shiva has not, the mourner’s work may be done by others in their own homes, and his employees may do it privately in his home. There is no need to comfort the mourner after the holiday for however many days he was comforted during the holiday; nevertheless, he should be visited.
220:1 Yom tov cancels the observance of shiva and of shloshim. Here’s how: if a person buried a relative before yom tov and started mourning, the arrival of the holiday cancels the mourning. This is so even if the burial was on erev yom tov in the afternoon; since he started mourning – even just taking his shoes off for a short time before yom tov – it interrupts his mourning. It is considered as if he already fulfilled the seven days of shiva; the first day of yom tov is treated like the eighth day and he continues on to thirty. Even if erev yom tov was on Shabbos and one received timely notification of a relative’s passing close to nightfall, and even though there is no public mourning on Shabbos, since he did some mourning – even though it was only in private – yom tov also cancels shiva for this.