sit (idly) by

sit (idly) by

To stand aside and refrain from acting or intervening. They may not have broken the law themselves, but the CEOs certainly sat by and allowed these illegal activities to happen unchecked. I feel so guilty for sitting idly by while my son was going through such a difficult time in his life.
See also: by, sit
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

sit by someone

to sit next to someone. May I sit by you? Come over here and sit by me.
See also: by, sit

sit idly by

 and stand idly by
to remain close, doing nothing to help. I do not intend to stand idly by while my children need my help. The wealthy man sat idly by while the poor people starved.
See also: by, idly, sit
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.

sit by

Also, sit idly by. Refrain from interfering, remain passive, as in I can't just sit by and let her get in trouble.
See also: by, sit
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

sit by

v.
To remain uninvolved; refrain from acting: I did the work while the others sat by and watched.
See also: by, sit
The American Heritage® Dictionary of Phrasal Verbs. Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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