The Sin of Forgetting

"وَلا تَكُونُوا كَالَّذِينَ نَسُوا اللَّهَ فَأَنسَاهُمْ أَنفُسَهُمْ أُوْلَئِكَ هُمُ الفَاسِقُونَ"

"نَسُواْ اللَّهَ فَنَسِيَهُمْ إِنَّ الْمُنَافِقِينَ هُمُ الْفَاسِقُونَ"

Between two painful punishments: forgetting oneself and being forgotten (ignored? for lack of a better translation) by Him.