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.
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]