Have somebody’s interests at heart
Definition 1 of 2
Pro Tip 1/3Empathetic Actions
Indicates actions are driven by deep understanding and concern for another's needs. 
The charity workers have the community's interests at heart, always listening to their concerns.
Pro Tip 2/3Personal Connection
Used when someone's care for others stems from a personal relationship, like family or friends. 
Despite his strict rules, Dad has our interests at heart.
Pro Tip 3/3Sincerity Implied
The phrase suggests genuine concern, not just superficial care. 
You can trust her advice; she has your interests at heart.