From Rabbi Sternbuch’s English Parsha sheet on Ki Savo:
And you shall come to the Kohen who will be in those days, and say to him.(26:3)That you are not ungrateful.(Rashi, ibid.)
The phrase “you are not ungrateful” seems surprising. Surely it would have been more appropriate to say that the person bringing the bikkurim is grateful to Hashem, not merely “not ungrateful.”
The fact is that even if we were to praise Hashem ceaselessly throughout our lives, it would still not be sufficient in light of Hashem’s boundless kindness to us despite all our sins and failure to comply with His will. However, although we cannot fulfill our duty to express our gratitude properly, if we recognize that our entire existence and all our assets in this world come solely from Hashem and are not the product of our actions, we will at least merit the title of someone who is “not ungrateful.”
Here in Eretz Yisrael, we are the constant recipients of Hashem’s open love and protection from our enemies who seek to destroy us. Although we can never thank Him enough, we should at least think and verbalize our realization that He is the Source of all this kindness, so that we will not be in the category of the ungrateful.