مَنْ عَمِلَ صَالِحًا مِّن ذَكَرٍ أَوْ أُنثَى وَهُوَ مُؤْمِنٌ
فَلَنُحْيِيَنَّهُ حَيَاةً طَيِّبَةً وَلَنَجْزِيَنَّهُمْ أَجْرَهُم
بِأَحْسَنِ مَا كَانُواْ يَعْمَلُونَ
Whoever works righteousness - whether male or female - while he (or
she) is a true believer (of Islâmic Monotheism) verily, to him We will
give a good life (in this world with respect, contentment and lawful
provision), and We shall pay them certainly a reward in proportion to
the best of what they used to do (i.e. Paradise in the Hereafter).
[surah an-Nahl 16: 97]
This verse clearly relates the adherence to Islam with being happy in
this world and the hereafter.
More..
http://www.islamscience.com/index.php?option=com_content&task=view&id=91&Itemid=37
AB