What is the meaning of "Nothing turns back the divine decree except supplication"?

Question:
Clarification of the issue of the connection between divine decree and supplication?

Answer:
Its meaning is that Allah (Exalted and Majestic is He) has decreed everything, and He may attach some matters to the actions of the servant. Thus, a person’s marriage may be decreed through his supplication, or decreed through a specific righteous deed of his, such as his Hajj, his prayer, or his charity.
Decrees are of two types:
One type is cut off, not attached to anything, such as death and the like. There is no way to change this.
The other type is attached: a person’s life may be prolonged because he will maintain family ties. Allah has written this, so He grants him success and facilitates for him what he was created for, such as maintaining family ties and giving charity, which are the causes of the lengthening of his life and his guidance.
As the Prophet (peace and blessings be upon him) said: , as for the people of happiness, they are facilitated for the deeds of the people of happiness, and as for the people of misery, they are facilitated for the deeds of the people of misery. These are matters linked to their decrees.