Is the meaning of "righteous son" in the noble Hadith "When a person's deeds are cut off except for three" restricted to his own children only, or does it include his relatives?

If a person dies, his deeds are cut off except for three: an ongoing charity (Sadaqah (definition) Jariyah), knowledge from which others benefit, or a righteous child who prays for him. The 'child' referred to here means the deceased's own children. However, the deceased also benefits from the supplications of others, whether relatives or strangers, for there is nothing in the hadith (definition) to indicate that he would not benefit from that.