How to Face Someone
A smile is incredibly important, especially when you’re the first one to give it to another. A baby that grew up without smiles will almost certainly have emotional issues. Everyone yearns for other people to show a bright face towards them, and when you’re the first one to initiate a warm smile, whether to a student, teacher friend, spouse, parent, or any other human being, it’s amazing.
That’s why the Sages say that you should always try and be the first to greet someone and that, in another remark, you should greet every person with a happy face.
By contrast, not having a happy face, like a judge who scowls at one of the litigants, can really cause him to unfairly lose his case.
"Do not show favoritism." Deuteronomy 16:19, from this week's Torah portion, Shoftim, Deuteronomy 16:18-21:9
* Based on Rav Wolbe on Chumash