"Time dilation is the slowing of time as perceived by one observer compared with another, depending on their relative motion or positions in a gravitational field"
"Imagine a spaceship traveling at 95% of the speed of light to a planet 9.5 light-years away. A stationary observer on Earth would measure the journey time as distance divided by speed, or 9.5/0.95 = 10 years. The spaceship crewmembers, on the other hand, experience time dilation and thus perceive the trip as taking only 3.12 years. (The math here is a little more complicated, but we'll get to it later.) In other words, between leaving Earth and reaching their destination, the crewmembers age a little over three years, while 10 years have passed for people back on Earth.
Although really striking situations like this call for enormously high speeds, time dilation occurs on a more modest scale for any kind of relative motion"
https://www.livescience.com/what-is-time-dilation
"Speed is not the only factor that changes relative to who is making the observation. Another consequence of relativity is the concept of time dilation, whereby people measure different amounts of time passing depending on how fast they move relative to one another.
Each person experiences time normally relative to themselves. But the person moving faster experiences less time passing for them than the person moving slower."
https://theconversation.com/why-does-time-change-when-traveling-close-to-the-speed-of-light-a-physicist-explains-197189
"The force of gravity treats time like taffy. The stronger its pull, the more gravity can stretch out time, making it pass more slowly."
https://www.snexplores.org/article/a-new-clock-shows-how-gravity-warps-time-even-over-tiny-distances
"The explanation comes down to what scientists call Gravitational Time Dilation. This effect measures the amount of time that has elapsed between two events by observers at different distances from a gravitational mass. In other words, time runs slower wherever gravity is strongest, and this is because gravity curves space-time."
http://thescienceexplorer.com/universe/how-gravity-changes-time-effect-known-gravitational-time-dilation
"But, beloved, be not ignorant of this one thing, that one day is with the Lord as a thousand years, and a thousand years as one day."
https://www.biblegateway.com/passage/?search=2%20Peter%203:8&version=KJV