Fear of Allah
Allah - by virtue of His Greatness - should be feared, as has been enjoined time and again in Quran as well as ahadith. Abbas the uncle of our blessed Holy Prophet has related that once he and others were sitting under a tree with the Holy Prophet when dry leaves began to fall from the tree till only green leaves remained. The Holy Prophet said. "This (tree) is like a believer who trembles with fear of Allah and so sheds his sins leaving behind only good deeds". (AI Targhib, p. 227. vol. 5. ref Baihaqi)
To create fear of Allah, we should think of His Power and Greatness, of the straits of earlier ummahs and of the chastisement mentioned in Quran and hadith for the disobedient ones. This shall create Allah's fear in the heart and prevent one from wrongdoing, sinning and unlawful acts, and one shall attain piety which is the basis of all good and of deliverance and salvation in this world and in the next. May Allah grant unto us the opportunity for it all Amen.