הלכות אבל

The Sabbath is counted as one of the days of mourning. Nevertheless, the laws of mourning are not observed on the Sabbath with the exception of private matters, e.g., veiling one's head, marital relations, and washing with hot water. With regard to matters which are obvious, however, the mourning laws are not observed. Instead, one may wear shoes, position his bed upright, and greet everyone.
If the mourner has another garment, he should change it. He should not wear a torn garment on the Sabbath even because of his father and mother. If he does not have a garment to change, he should turn the tear to the other side.

When may one position his bed upright on Friday? From the afternoon onward. Nevertheless, one should not sit on the upright bed until nightfall. Even when there remains only one day for the seven days of mourning, one should overturn the beds again on Saturday night.

On the festivals and similarly, Rosh HaShanah and Yom Kippur, we do not observe any of the mourning rites at all. Moreover, whenever anyone buries his dead even a small amount of time before a festival or before Rosh HaShanah or Yom Kippur, the decree requiring him to observe seven days of mourning is nullified.
Thus after Rosh HaShanah and Yom Kippur, a mourner counts 23 days. After Pesach, he counts16 days - for the seven days of mourning are nullified and the seven days of the festival are equal to 14. Similarly, if the deceased was buried before Shavuos, the mourner counts 16 days afterwards. For even though the holiday is only one day, since it is a festival, it is counted as seven days.

When a person buries his dead before Sukkos, he should count only nine days after the festival. For Shemini Atzeret is a holiday in its own right. Thus the first day concludes the seven days, then come the seven days of the holiday, and the eighth day is considered as a festival. Thus there are 21 days.

When a person buries his dead seven days before any one of the festivals or seven days before Rosh HaShanah or Yom Kippur, the decree requiring him to observe the 30 days of mourning is nullified. He is permitted to cut his hair and launder his garments on the day preceding the festival or Yom Kippur. The rationale is that a portion of the day is considered as the entire day. After the holiday, he does not count any other days of mourning.
If, however, he is mourning for his father or mother - even if they died more than 30 days before the festival - he may not cut his hair until it grows uncontrolled or until his friends rebuke him. The festivals do not nullify this measure.

When the sixth day of mourning falls on the day before the festival - needless to say, this law applies if the fifth or the third day falls on that day - he may not cut his hair. The festival nullifies only the decree requiring him to mourn for seven days. He is not permitted to wash, anoint himself, or perform any other practice forbidden during the days of mourning until the onset of the festival. The festival concludes the seven days of mourning. After the festival, he concludes all 30 days from the day of the death. During them, he is forbidden to perform any of the five practices mentioned in Chapter 6.

The following rules apply when the seventh day of mourning falls on the day before a festival and that day is the Sabbath. The decree requiring him to observe the 30 days of mourning is nullified and he may cut his hair in the midst of the holiday. For he was held back by forces beyond his control since he cannot cut his hair on the Sabbath. Similarly, one may cut one's hair after Shavuot or after Rosh HaShanah and Yom Kippur, for the decree requiring him to observe the 30 days of mourning has been nullified and he may cut his hair whenever he desires.

When a person buries his dead in the midst of a festival, the laws of mourning do not apply to him. He does not observe the mourning rites in the midst of the festival. Instead, after the festival he begins to count the seven days of mourning and observes all of the mourning rites at that time. He counts the 30 days of Sheloshim from the day of the burial. In the days that remain from these 30 days, he observes all the restrictions required.

When a person buries his dead in the midst of a festival, the laws of mourning do not apply to him. He does not observe the mourning rites in the midst of the festival. Instead, after the festival he begins to count the seven days of mourning and observes all of the mourning rites at that time. He counts the 30 days of Sheloshim from the day of the burial. In the days that remain from these 30 days, he observes all the restrictions required.

In the above situation, in places where the holidays are observed for two days, one should count seven days from the second day of the final days of the festival. Since its observance is a Rabbinic institution, it is included in the reckoning and he need count only six days afterwards. He counts the 30 days of Sheloshim from the day of the burial as stated above.

When a person buries his dead on the second day of a holiday which is the final day of a festival or on the second day of Shavuot, he should observe mourning rites, for the observance of the second day of a festival is a Rabbinic institution and the observance of mourning rites on the first day is a Scriptural obligation. Hence the observance of a positive Rabbinic commandment is superseded by the observance of a positive Scriptural commandment.
If, however, one buries his dead on the second day of Rosh HaShanah, he should not observe the mourning rites. For the two days of Rosh HaShanah are considered as one long day, because of the rationale explained in Hilchot Kiddush HaChodesh.