keep back
Don't release it
To keep back is to hold something in reserve rather than releasing or revealing it.
You might keep back information, keep back tears, or keep back part of your paycheck for savings.
It also means to restrain or prevent from advancing: Police kept the crowd back from the scene.
The phrase suggests deliberate withholding—something could come forward but doesn't.
Keep from being seen
refuse · retain · omit · censor · redact · classified · confidential · embargo
conceal
Keep from being seen
deny · refuse · retain · omit · censor · redact · classified · confidential · embargo · silence
detain
Hold in custody
cordon · barrier · crowd control · prevent · stop · halt · contain · restrict · limit · confine
savings
Accumulated money kept
nest egg · rainy day · emergency fund · provision · contingency · surplus · buffer · safeguard · set aside · put away