Say not: “When I have free time I shall study”, for you may perhaps never have any free time
Do not unto others that which is hateful unto thee.
Take care of yourself - you never know when the world will need you.
What you yourself hate, don't do to your neighbor. This is the whole law; the rest is commentary. Go and study.
The shy man will not learn; the impatient man should not teach.
Judge not thy friend until thou standest in his place.