All praise is due to Allah, and may peace and blessings be upon the Messenger of Allah. To proceed:
What Allah, Exalted be He, has written in the Preserved Tablet (Al-Lawh Al-Mahfuz) does not change or alter. He says:
“No calamity befalls the earth or yourselves except that it is in a Book before We bring it into existence.”
The Prophet ﷺ also said:
“The pens have been lifted and the pages have dried.”
However, there are two types of divine writing:
First: What is recorded in the Preserved Tablet. This does not change because it corresponds to the eternal knowledge of Allah, Exalted be He.
Second: What the angels record of the decrees made known to them. This may undergo erasure and confirmation according to certain causes. Allah says:
“Allah erases what He wills and confirms what He wills, and with Him is the Mother of the Book.”
Among these causes is what has been reported in the Sunnah: maintaining ties of kinship is a means of increasing provision and extending one's lifespan, and supplication is a means of warding off calamity.
This does not mean that Allah's knowledge or what is recorded in the Preserved Tablet changes. Rather, Allah, Exalted be He, knew and recorded from the outset that a servant would supplicate or maintain ties of kinship, and that this would become a means of obtaining good or averting harm.
The same applies to all other means. The provision decreed for a servant may depend on his efforts and work, or it may come without such effort. All of this falls within Allah's decree. Among the means of obtaining provision are working and earning, supplication, reliance upon Allah, treating people kindly, and maintaining ties of kinship.
Therefore, the correct statement is: Nothing changes what has been firmly established in the Preserved Tablet. However, Allah, Exalted be He, has made supplication, acts of obedience, maintaining ties of kinship, and other means causes through which the decrees recorded by the angels may change. All of this was already known and recorded by Allah beforehand.
A servant should therefore never abandon supplication or effort on the grounds that everything has already been decreed, because supplication, effort, and the means themselves are all part of the divine decree.
And Allah knows best.