Since God is the Creator of everything and every creature, and He initiates creation and resurrection, and mixes sorrow with happiness, ugliness with beauty, assets with miseries and has made this principle of juxtaposition as the basis for perfection, “you have to resort only to Him and devote your worship just to Him and have your love only for Him and fear Him solely”.
It is because this exclusive devotion is a sign of your gratitude and of your perfect monotheistic belief, which is not given to everybody. God in His Qur’an has trained the Prophet in this manner:
"قُلْ إِنَّ صَلَاتِي وَنُسُكِي وَمَحْيَاي وَمَمَاتِي لِلَّهِ رَبِّ الْعَالَمِينَ لَا شَرِيكَ لَهُ وَبِذَلِكَ أُمِرْتُ وَأَنَا أَوَّلُ الْمُسْلِمِينَ قُلْ أَغَيْرَ اللَّهِ أَبْغِي رَبًّا وَهُوَ رَبُّ كُلِّ شَيْءٍ وَلَا تَكْسِبُ كُلُّ نَفْسٍ إِلَّا عَلَيْهَا وَلَا تَزِرُ وَازِرَةٌ وِزْرَ أُخْرَى ثُمَّ إِلَى رَبِّكُمْ مَرْجِعُكُمْ فَيُنَبِّئُكُمْ بِمَا كُنتُمْ فِيهِ تَخْتَلِفُونَ"
“Say: Surely my prayer and my sacrifice and my life and my death are all for Allah, the Lord of the worlds. No associate has He; and this am I commanded, and I am the first of those who submit. Say: Shall I seek a lord other than Allah? And He is the Lord of all things; and no soul earns evil but against itself, and no bearer of burden shall bear the burden of another; then to your Lord is your return, so He will inform you of that in which you differed [Qur’an 6:162-164].
"قُلْ إِنَّ صَلَاتِي وَنُسُكِي وَمَحْيَاي وَمَمَاتِي لِلَّهِ رَبِّ الْعَالَمِينَ لَا شَرِيكَ لَهُ وَبِذَلِكَ أُمِرْتُ وَأَنَا أَوَّلُ الْمُسْلِمِينَ قُلْ أَغَيْرَ اللَّهِ أَبْغِي رَبًّا وَهُوَ رَبُّ كُلِّ شَيْءٍ وَلَا تَكْسِبُ كُلُّ نَفْسٍ إِلَّا عَلَيْهَا وَلَا تَزِرُ وَازِرَةٌ وِزْرَ أُخْرَى ثُمَّ إِلَى رَبِّكُمْ مَرْجِعُكُمْ فَيُنَبِّئُكُمْ بِمَا كُنتُمْ فِيهِ تَخْتَلِفُونَ"
“Say: Surely my prayer and my sacrifice and my life and my death are all for Allah, the Lord of the worlds. No associate has He; and this am I commanded, and I am the first of those who submit. Say: Shall I seek a lord other than Allah? And He is the Lord of all things; and no soul earns evil but against itself, and no bearer of burden shall bear the burden of another; then to your Lord is your return, so He will inform you of that in which you differed [Qur’an 6:162-164].
