Allah Almighty is the One Who expands and constricts and Who elevates and lowers, according to His predestination. This does not mean, however, that such things do not happen due to the people themselves and their acts. They do certain things and find their consequences. The Prophet (may Allah’s peace and blessings be upon him) combined these two meanings in the Hadīth that reads:
“Whoever loves to have his sustenance expanded and his term of life prolonged should maintain ties of kinship.”
[Narrated by Al - Bukhāri and Muslim]
So, the expansion of sustenance lies in the Hand of Allah; whereas maintaining ties of kinship is a cause to be fulfilled by the person himself.