There are a number of stages of decree - eternal decree, life time decree, annual decree and daily decree. So, in which stage can qadar be changed by the Will of Allah?
That which is in the Lawh al-Mahfooz can never be changed. The Prophet ﷺ said, “The pens have been lifted and the pages have dried.”
As for the pages which are in the hands of the angels, Allah may command His angels to change it because of an act of worship that a Muslim does or because of a sin that he commits. However, in the end, it will not be anything other than that which was decreed from eternity. This is indicated by the verse in which Allah says:
يَمۡحُواْ ٱللَّهُ مَا يَشَآءُ وَيُثۡبِتُۖ وَعِندَهُ ۥۤ أُمُّ ٱلۡڪِتَـٰبِ
“Allah blots out what He wills and confirms (what He wills). And with Him is the Mother of the Book (Al‑Lawh Al‑Mahfooz).”
The Prophet ﷺ urged us to do some acts of worship which have an effect of increasing a person’s lifespan, such as upholding ties of kinship, and he said that du’a can repel the divine decree. What this means is that Allah knew from the beginning that His slave would engage in this act of worship, so He decreed for him a long life or a blessed provision. Likewise, a person may commit a sin because of which he is deprived of provision, and Allah knew that and decreed it from eternity and decreed it according to His knowledge.
The Prophet ﷺ said:
“Nothing increases one’s lifespan except righteousness and nothing repels the divine decree except du’a; and a man may be deprived of provision by a sin that he commits.”
And Allah knows best.
 Tirmidhi: 2516
 Quran 13:39
 Classed as saheeh by al-Albani in Saheeh Ibn Majah (4022)< Back to Questions