خَفِ اللّهَ يُؤمِنْكَ، وَ لا تأمَنْهُ فَيُعَذِّبَكَ
Fear Allah and he will make you safe, but if you do not fear him he will punish you.
Fearing Allah and avoiding sins is a cornerstone in the practice of Islam. In sermon 64 of Nahjul Balagha, Ali bin abi Talib said:
O creatures of Allah! Fear Allah and anticipate your death by good actions. Purchase everlasting joy by paying transitory things – pleasures of this world. Get ready for the journey, for you are being driven, and prepare yourselves for death, since it is hovering over you.
We discussed the importance of keeping hope in Allah in a previous post. Fear and hope should both be present in one’s heart:
Man’s psyche should contain a perfect balance of fear and hope.
Here is a good article about the same subject.