Apologies for any confusion caused by my previous statement. Let's clarify the relationship between mass, gravity, and time dilation.
In the theory of general relativity, mass and energy are the sources of gravitational fields, rather than the causes of time dilation. Massive objects curve the fabric of spacetime, and this curvature determines how objects move within the gravitational field.
The presence of mass and energy causes spacetime to be curved, and objects moving through this curved spacetime experience the effects of gravity. This curvature affects both the motion of objects and the passage of time.
Time dilation in the presence of mass occurs because the curvature of spacetime around a massive object affects the flow of time. Near a massive object, such as a planet or star, spacetime is more strongly curved, resulting in a slower passage of time relative to a less curved region of spacetime.
To summarize, it is the curvature of spacetime caused by mass that leads to time dilation, not the other way around. Mass and energy cause the curvature of spacetime, which, in turn, affects the flow of time and gives rise to the phenomenon of time dilation in the presence of gravity.