Time is a silent, submissive force. الدَّهْرُ أَطْرَقُ مُسْتَتِبُّ.

Meaning, it is silent, submissive, and yielding. Bashar ibn Burd said:
A year, let not tomorrow deceive you... a year, for time is silent and forgiving.
Catch the one with malice in his moment of weakness... and when a she-camel gives milk, milk her.
------------------------------------------------------------------------------------------------The proverb "Time is silent and still" means that time may appear calm, still, and stable, but it works its magic quietly, waiting and turning a blind eye until the opportunity arises. It refers to the apparent tranquility and the continuation of events without fanfare.
There is no English proverb that perfectly matches it, but the closest equivalents are:
"Still waters run deep."
— That is, apparent stillness may conceal an underlying influence or force, and this proverb is closest in spirit to the Arabic proverb.
"Time works in silence."
— A direct, non-traditional expression.
"Time quietly takes its course."
"Time will tell."
Therefore, the best English equivalent is:
"Still waters run deep."
If the intention is to emphasize that time moves quietly and steadily, the most appropriate expression is:
Time quietly takes its course.
That is, time proceeds in its course calmly and continuously, until it reaches its end.
---------------------------------------------------------------------------------------------------------
أي مُطْرِق مُغْضٍ منقاد، قال بشار ابن بُرْد:
عَامِ لا يَغْرُرْكَ يَوْمٌ من غدٍ ... عامِ إِنَّ الدَّهْرَ يُغْضِي وَيَهبْ
صَادِ ذَا الضِّغْنِ إلى غِرَّتِهِ ... وَإِذَا دَرَّتْ لَبُونٌ فَاحْتَلِبْ