Surah Al Baqarah Tafseer

وَأَقِيمُواْ الصَّلَةَ وَاتُواْ الزَّكَاةَ وَمَا تُقَدِّمُواْ لَانفُسِكُم مِّنْ خَيْرٍ تَجِدُوهُ عِندَ اللّهِ

And perform the Salah and give the Zakah, and whatever of good you send forth for yourselves before you, you shall find it with Allah.

Allah encouraged the believers to busy themselves in performing deeds that would bring them benefit and reward on the Day of Resurrection, such as prayer and paying Zakah. This way, they will gain Allah's aid in this life and on a Day when the witnesses testify,

يَوْمَ لَا يَنفَعُ الظَّـلِمِينَ مَعْذِرَتُهُمْ وَلَهُمُ الْلَّعْنَةُ وَلَهُمْ سُوءُ الدَّارِ

The Day when their excuses will be of no profit to the Zalimin (wrongdoers). Theirs will be the curse, and theirs will be the evil abode (i.e. painful torment in Hell-fire). (40:52)

This is why Allah said,

إِنَّ اللّهَ بِمَا تَعْمَلُونَ بَصِيرٌ

Certainly, Allah sees what you do.

meaning, that He is never unaware of the deeds of any person, nor will these deeds be lost by Him. Whether deeds are righteous or evil, Allah will award each according to what he or she deserves based on their deeds