Almighty Allah commands in the Glorious,“O You Who Believe! Fear ALLAH”
In other words, instill the fear of ALLAH in your hearts and be obedient to HIM. The
Holy Prophet Muhammad  said, “When a servant trembles in the fear of ALLAH, then his sins fall off his body like the leaves fall off a tree when it is shaken.” .
When Hazrat Umar-e-Farouk would listen to verses of the Holy Quran, then he would become unconscious in the fear of Allah
Once, he took a blade of grass in his hand and said,“How I wish I were a blade of grass, something that is not worthy anything. How I wish that my mother had not
given birth to me.”
He would cry so intensely in the fear of ALLAH, that the flow of tears caused two scars to be formed on his face.(Mukashafatul Quloob – Imam Al Ghazzali radi Allahu
anhu)
We should try to instil in our hearts the true fear for the Almighty ALLAH. If a person truly fears ALLAH, then only will he be able to be obedient to ALLAH. Without the fear of ALLAH, our hearts will become a sanctuary for shaitaan.The time will come, when every one of us must stand before ALLAH, with our good and bad deeds, so FEAR
ALLAH! FEAR ALLAH!

SINCERITY IN IBAADAT for Allah

is very important for a believer. When one worships Almighty Allah, he or she must be completely sincere and
dedicated.
When a person stands in Namaaz, then he should remember that he is standing in the exalted court of Allah.
The pious servants of Allah taught us how to make Ibaadat with sincerity. One such example is Hazrat Sayyiduna Imam Zainul Abideen .
He used to perform one thousand rakaats of nafil salaah every night. One night whilst he was performing his nafils, his house caught on fire. The people were rushing around
trying to put out the fire, but he continued his Namaaz with total sincerity. After he completed his salaah, the people told him that his house had caught on fire and yet
he continued reading his Namaaz without any showing any sign of panic. He said, “You were trying to extinguish this fire, and I was trying to extinguish the fire of the hereafter.” [Khazinatul Asfiyah vol.1 pg.31]