tell him or her that
Mi madre estará preocupada si no llamo para decirle que llegué bien.
My mother will be worried if I don't call to tell her I arrived safely.
I want to tell her that I love her.
Decidí no llamar a Bleeker para decirle que iba a tener el niño.
I decided not to call Bleeker to tell him I was going to have the baby.
— Juno: Crecer, correr y tropezar (2007)
No me decido a decirle que es imposible para él obtener ese trabajo.
I can't bring myself to tell him that it's impossible for him to get that job.
Ella le escribió para decirle que lo amaba.
She wrote to him to tell him that she loved him.