put one's oar in

put (one's) oar in(to) (something)

1. To offer or express one's opinion (on some matter), even though it was not asked for or desired. I don't know why you feel you have to put your oar into every dispute Terry and I are having. The members of the board are perfectly capable of arriving at a decision of their own accord, so I'll thank you for not putting your oar in, Tom.
2. To involve oneself in an intrusive or nosy manner into something that is not one's business or responsibility. I wish my neighbors would quit putting their oars in and just leave us alone! Liam, don't put your oar into your brother's affairs—he can manage well enough on his own.
See also: oar, put
Farlex Dictionary of Idioms.

put one's oar in

Interfere with something or insert one's opinion, as in I'll thank you not to put your oar in when we're discussing a private matter. This term, referring to helping to row a boat, was first recorded in Charles Coffey's 1731 play The Devil to Pay: "I will govern my own house without your putting in an oar."
See also: oar, put
The American Heritage® Dictionary of Idioms by Christine Ammer.

put one's oar in, to

To insert one’s opinion; to interfere in someone else’s business. This term, with its analogy to contributing one’s efforts to rowing a boat, dates from the late sixteenth century. Charles Coffey used it in his play The Devil to Pay (1731): “I will govern my own house without your putting in an oar” (1:2).
See also: oar, put
The Dictionary of Clichés by Christine Ammer
See also:
  • put (one's) oar in(to) (something)
  • put oar in
  • put your oar in (something)
  • put/stick your oar in
  • put one's oar in, to
  • (one's) cake is dough
  • under control
  • sell (one's) soul (to the devil)
  • sell your soul
  • have just one oar in the water