I have two.
1) When I went away to college, the last thing my Dad said before I drove off was, "Remember where you came from." I gave my son that same advice when he went away to college.
2) When my son (who's named after my Dad) was about 4 years old, I was leaving for work one day and I said, "Bye Joe - be a good boy today." He replied, "Bye Dad - be a good man today."
In my 50+ years on this planet, nobody has ever given me better advice than those two nuggets of wisdom.