The importance of protecting one's remembrance of Allah (dhikr)

فَٱتَّخَذْتُمُوهُمْ سِخْرِيًّا حَتَّىٰٓ أَنسَوْكُمْ ذِكْرِى وَكُنتُم مِّنْهُمْ تَضْحَكُونَ

But you took them in mockery to the point that they made you forget My remembrance, and you used to laugh at them.