The passuk says, “yisa Hashem panav eilecha.” Chazal explain that Hashem favors Klal Yisrael because we praise Him by bentching after eating only a k’zayis of bread even though He only commanded us to bench after being fully satisfied.
Reb Bunim of P’shischa explained the p’nimiyus of this Gemara as follows: When one gets a present from a very esteemed person, it has great value even if the present is very small. When the Yidden bentch on a k’zayis of bread, it’s as if they are telling Hashem, “Even when You give us only a small amount, we value it very much because we know it came from You!”
When Hashem hears this, He treats us the same way by considering even our small avodahs – even if they’re “less than a k’zayis” —with great value!
This article was found in Nekuda Tova Issue 83.