ומלפניך מלכנו ריקם אל תשיבנו (בברכת שמע קולנו)
It is possible to understand these words according to the Zohar that HaShem does not rest His Presence except on a matter that is already in this world, even if it is only a small item. The main concept is that HaShem adds His Blessing to increase something that is small (since all is small in comparison) to Him. However, He does not rest His Presence on something this is empty, since that would create a new item (see the Taz Hil. Chanukah 570:1).
Regarding this matter, one can appreciate the Rambam regarding the laws of “Going up to the Temple” during the Yomim Tovim. Rambam learns the law (Chagigah 1:2) that no minimum amount is established in what one brings to the Holy Temple, and relies on the verse (Devarim 16, 17) איש כמתנת ידו. However, Rambam does not rely on the previous verse לא יראה פני ה' ריקם , even though this seems to imply any amount would be acceptable.
In the context of many other places (gifts to an emancipated slave or when the Jews left Egypt), the word ריקם does not imply any amount, no matter how small. Rather, in these places ריקם does not imply a minimum amount since the opposite of ריקם implies a large amount. Thus, Rambam does not use the verse containing ריקם to teach a minimum amount, but a different verse.
