Know that belief is the seed of spiritual happiness. It begins with a belief in the meaning of the testimony of faith, which states that there is no god but God, and Muhammad is the Messenger of God.
Know that you have been created and that your Creator, the one God, is the master of all creation.
You have an allotted time in the physical world; and at death, the spirit separates from the body, and will go to heaven or hell.
God is All-Powerful. Everything in existence is under His control. All that is in the world is by His desire and Will.
Know that God is transcendent. Nothing is like God, without form, beyond the conception of mind or imagination.
God occupies no space and cannot be limited by space.
God knows everything: from the grains of sand in the desert to the leaves on the trees, and even the myriad thoughts that pass through every human mind.
God sees and hears everything. God also speaks but not by mouth, tongue, and lips. Rather, His speech is pure and superior. It is in the soul of a person.
Finally, know that God gave humanity messengers; the last was Prophet Muhammad.
God sent these messengers to disclose the fruit of spiritual happiness, which grows from the seed of belief.
SOURCE: https://aboutislam.net/spirituality/belief-is-the-seed-of-spiritual-happiness/
