“Say to all the people of the land and to the Kohanim: When you fasted and lamented in the fifth and seventh months all these seventy years, did you fast for my benefit?” ZECHARIAH 7:5 (The Israel Bible™)
In the fourth year of King Darius’ rule, a delegation is sent to the Prophet Zecharya (Zechariah) in Yerushalayim (Jerusalem) by the Jews who remained in Babylonia. They asked Zecharya if they must continue fasting and mourning the destruction of the first Temple since the Jewish people had returned to the Land of Israel and had begun rebuilding the Beit Hamikdash (Holy Temple). The prophet’s response is clear. In Hashem’s (God) eyes, fasting and other external signs of mourning have no value if not accompanied by sincere repentance and ethical behavior. This answer was directed to the inhabitants of the Land of Israel, as well. The Jews in this period made the physical return to the Land of Israel, but their actions needed to match the spirituality and morality required of the inhabitants of the Promised Land.