Fasting has been prohibited on doubtful day which is

Fasting has been prohibited on a doubtful day, which is the 30th of Sha'aban in the Islamic calendar. This is because the timing of the new moon sighting to determine the start of Ramadan can sometimes be uncertain, and there is a risk of fasting on the wrong day if the moon is not sighted correctly. Fasting on a doubtful day is not considered a good deed in Islam because it does not have the desired effect of bringing one closer to Allah. Therefore, it is important for Muslims to be cautious and follow the guidance of their local religious authorities to ensure that they fast on the correct day.