Since our acceptance of Islam and the revelation of this verse in which Allah has shown annoyance to us:" Has not the time yet come for the believers that their hearts should be humble for the remembrance of Allah?" (lvii. 16), there was a gap of four years.  

أَنْ عَاتَبَنَا اللَّهُ بِهَذِهِ الآيَةِ { أَلَمْ يَأْنِ لِلَّذِينَ آمَنُوا أَنْ تَخْشَعَ قُلُوبُهُمْ لِذِكْرِ اللَّهِ} إِلاَّ أَرْبَعُ سِنِينَ