O ye who believe! Fear Allah, and let every soul look to what (provision) He has sent forth for the morrow. Yea, fear Allah: for Allah is well-acquainted with (all) that ye do.
The “fear of Allah” is akin to love; for it means
the fear of offending Him or doing anything wrong that
will forfeit His Good Pleasure. This is Taqwa, which
implies self restraint, guarding ourselves from all sin,
wrong, and injustice, and the positive doing of good.
The positive side of Taqwa, or “fear of Allah”
(see last note) is here emphasised.
It is not merely a feeling or an emotion: it is an act, a
doing of things which become a preparation and
provision for the Hereafter,-the next life, which may be
described as “the morrow” in relation to the present Life,
which is “to-day”.
The repetition emphasises both sides of
Taqwa: “let your soul fear to do wrong and let it do
every act of righteousness; for Allah observes both your
inner motives and your acts, and in His scheme of things
everything will have its due consequences.
Yusuf Ali, Abdullah. Translation and Commentary of the Quran. (surah 59 verse 18 Quran Arabic with English Translation & Commentary (Tafsir) by Abdullah Yusuf Ali, Free Download (quran4u.com)