Hi, OctavO! Welcome.
I should dispel the suffering of others because it is suffering like my own suffering. I should help others too because of their nature as beings, which is like my own being. When happiness is liked by me and others equally, what is so special about me that I strive after happiness only for myself? When fear and suffering are disliked by me and others equally, what is so special about me that I protect myself and not the other? Shantideva, Bodhi[sattva]caryavatara 8.94-96