in one's interest

in (one's) (own) interest

Beneficial to one. It would be in your interest to have your lawyer review the contract before you sign it.
See also: interest
Farlex Dictionary of Idioms.

in one's interest

Also, in the interest of one; in one's own interest; in one's best interest. For one's benefit or advantage, as in It's obviously in their interest to increase profits, or Is this policy in the interest of the townspeople? or I suspect it's in your own best interest to quit now. [Early 1700s]
See also: interest
The American Heritage® Dictionary of Idioms by Christine Ammer.
See also:
  • in (one's) (own) interest
  • in interest
  • in the interest of (one)
  • in the interest of
  • in (one's) best interest
  • declare an interest
  • declare an/(one's) interest
  • of interest
  • vested interest
  • in the interest of justice