Leaving Food On The Plate

Is it sunnah to not finish all the food on your plate and leave some food for next time? Reason I ask is that someone told me this is a very good thing to do, and someone else said this is illogical, please clarify this, insha'Allah.

Walaikum assalam,

The sunna is to finish all the food one took on one's plate.

Leaving food is from wastefulness: leaving just a little is better not to; leaving more than this is blameworthy; that which would be considered 'excessively wasteful' is sinful.

This is if the food on one's plate got there of one's own accord. Otherwise, the waste is from the one who gave too much...

Walaikum assalam,
Faraz Rabbani