לע"נ סבי ר' אלכסנדר זושא בן ר' יוסף
The pasuk says
"וגם עבדך נזהר בהם בשמרם עקב רב".
Also your servant was careful in them [the mitzvos] for in keeping them there is great reward.
Torah on the surface is merely a great guidebook for laws of governing a civil society. It teaches not to steal, kill etc. etc.
But we have to know that Torah is so much more than that. Keeping Torah elevates one to a high spiritual plateau. So the pasuk says that your servant was careful with the laws of the Torah which are not just about how to conduct life here but actually contain tremendous eternal reward because of their spiritual value.
Here is the pnimiyus-dike way of explaining this pasuk.