Precaution (taqwa) has three facets:
1. Precaution by dependence on Allah, which means leaving behind contradiction and going beyond any shade of doubt, and this is the precaution exercised by the highest.
2. The precaution of Allah, which means to abandon all doubtful matters and to leave the forbidden (haram) alone; this is the precaution of the elite.
3. The precaution of the Fire and Punishment, which results in leaving alone what is forbidden; this is the precaution of the general public.
Precaution is like water flowing in a river. The three levels of precaution are like trees of every colour and variety planted on the bank of that river, each tree absorbing water from that river according to its essence, capacity, delicateness and thickness.
Then the benefits, which creatures take from these trees and fruits, are according to their value and worth. Allah said,
وَزَرْعٌ وَنَخِيلٌ صِنْوَانٌ وَغَيْرُ صِنْوَانٍ يُسْقَى بِمَاء وَاحِدٍ وَنُفَضِّلُ بَعْضَهَا عَلَى بَعْضٍ فِي الأُكُلِ
Precaution in acts of obedience to Allah is like water for the trees, and the natures of the trees and their fruits in their colours and tastes are like the measures of belief. Whoever has the highest degree in belief and the purest nature with respect to the soul has the greatest precaution. He who is precautious has the purer and more sincere worship: whoever is like that is nearer to Allah.
But every act of devotion that is founded on something other than precaution comes to nothing. Allah said,
أَفَمَنْ أَسَّسَ بُنْيَانَهُ عَلَى تَقْوَى مِنَ اللّهِ وَرِضْوَانٍ خَيْرٌ أَم مَّنْ أَسَّسَ بُنْيَانَهُ عَلَىَ شَفَا جُرُفٍ هَارٍ فَانْهَارَ بِهِ فِي نَارِ جَهَنَّمَ
The explanation of precaution is to avoid entering an affair which contains no harm simply out of fear of one which does. It is, in reality, obedience without rebellion, remembrance without forgetfulness, knowledge without ignorance, and it is accepted by Allah and not rejected.