Rabin bar Ada said in the name of Rav Yitzchak: If someone is accustomed to coming to shul and does not come for one day, Hashem asks why he did not come; as it says (Yeshayahu 50:10), “Who among you fears Hashem, who listens to the voice of His servant, who went to a place of darkness and has no light?” This refers to someone who is accustomed to going to shul to hear the shaliach tzibbur, Hashem’s servant, and now “went to a place of darkness,” meaning that he did not come to shul. If he went in order to do a mitzvah, it will be light for him, but if he went for some personal reason, then it will not be light for him. And the passuk concludes, “Let him trust in the Name of Hashem,” implying that the reason Hashem is angry at him is that he should have trusted in Hashem and gone to shul, and he did not trust in Hashem enough.
(Brachos 6b)
