Mishnah/Seder Nezikin/Tractate Avot/Chapter 4/3
[Ben Azai] would say:
Do not disparage anyone, and do not shun any thing.
For you have no man who does not have [his] hour,
and you have no thing which does not have a place.
or: treat no one lightly, think nothing is useless, for everyone have their moment and anything has it's place