Why did not He (swt) say: The good reward of this world and the good reward of the hereafter? Because there is nothing in the world that you evaluate as good, good is what remains, Allah (swt) gives you the reward of this world, but this reward does not remain, He (swt) gives you health and strength in this world… but it is not permanent, but when He talks about the hereafter, He (swt) says: The good reward of the hereafter, to pay your attention to the eternal immortal.
وَاللّهُ يُحِبُّ الْمُحْسِنِينَ {And Allah loves the doers of good}: The doer of good is the benefactor to the poor and who gives the others, as Allah (swt) says:
إِنَّ الْمُتَّقِينَ فِي جَنَّاتٍ وَعُيُونٍ (15) آخِذِينَ مَا آتَاهُمْ رَبُّهُمْ إِنَّهُمْ كَانُوا قَبْلَ ذَلِكَ مُحْسِنِينَ (16) كَانُوا قَلِيلًا مِّنَ اللَّيْلِ مَا يَهْجَعُونَ (17) وَبِالْأَسْحَارِ هُمْ يَسْتَغْفِرُونَ (18) وَفِي أَمْوَالِهِمْ حَقٌّ لِّلسَّائِلِ وَالْمَحْرُومِ
{(15) Indeed, the righteous will be among gardens and springs, (16) Accepting what their Lord has given them. Indeed, they were before that doers of good. (17) They used to sleep but little of the night, (18) And in the hours before dawn they would ask forgiveness. (19) And from their properties was [given] the right of the [needy] petitioner and the deprived.} (Adh-Dhaariyat: 15-19)