Venerable Ru Jun mentions this in his discourse.
From 1 min 4s mark:
As told by Buddha, these 8 kinds of people are:
- One’s own father
- One’s own mother
- Buddha
- Disciples of Buddha
- People who have come from a long distance
- People who are going somewhere far
- Sick people
- People who care for the sick
Listen to the rest of this story on Karma about the 孝順的大白象 (The Filial White Elephant):