Do not separate yourself from the community; 

Do not be sure of yourself until the day of your death;

Do not judge your fellow man until you find yourself in his place;

Do not say anything that cannot [presently] be understood because [you believe] it will ultimately be understood.

And do not say, "When I will have leisure, I will study": perhaps you will never have leisure.

Hillel, Pirkei Avot, 2:5