Is a prayer in which one's devotion to Allah Almighty is incomplete unacceptable?

The worshiper must be humble and tranquil in their prayer, for humility is the spirit of prayer and it is one of the characteristics of the successful believers. If the worshiper neglects tranquility and humility, pecking at the prayer, their prayer becomes invalid. However, if the worshiper is tranquil but experiences some intrusive thoughts and forgetfulness, their prayer is valid, but its reward is diminished to the extent of what they did not comprehend from it. Tranquility must be such that every joint returns to its place in bowing, prostrating, standing after bowing, and sitting between the two prostrations. The proof for this is the hadith of the Prophet (PBUH) to the man who was not tranquil in his prayer: "Pray, for you have not prayed."