The Determination of the Days of the Festival

Some people add to the days of the festival. Is this addition correct?The Shaykh: The first day is the festival, and there is no problem with it. The second and third days are also the festival;By the saying of the Prophet (peace and blessings be upon him): (Leave them alone —Meaning: the two women who were singing — for they are days of the festival) The word "days" is a plural, and the minimum for a plural is three. Therefore, there is no harm in a person considering all three days as the festival, except in one matter, which is fasting.As for fasting, if he said: He will not fast on the second and third days of Shawwal; because fasting on them is forbidden, just like on the festival day. So this is not permissible. As for Dhu al-Hijjah, it is well known that fasting on the Days of Tashreeq is not permissible. If we add three days to the day of the festival, it becomes four. Perhaps you are referring to the celebrations that people perform,So we say: which are three days in the two festivals: 'Id al-Adha and 'Id al-Fitr.