Time is more effective in changing things. الدَّهْرُ أَبْلَغُ في النَّكِيرِ.

By changing things, he means that time changes everything it encounters.
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The Arabic proverb "Time is more eloquent in denial" means that time is more capable than any preacher or critic of bringing about change, and that time is sufficient to alter circumstances and reveal truths.
The closest English equivalents are:
Time changes all things.
Time takes its toll.
Time will tell.
Time is the great healer. (If the context relates to the disappearance of an effect or pain.)
Nothing withstands the ravages of time.
Nothing can withstand the ravages of time. (If the intended meaning is change and corruption.)

The closest English proverb to the meaning of the Arabic proverb is:
Time changes all things.
Or, in a more eloquent and common form:
Time takes its toll.
Both convey the meaning that time is more effective in bringing about change and transformation than any denial or blame.
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يعني بالنكير الإنكار والتغيير، يريد أن الدهر يغير ما يأتي عليه.