Chasidut for Eruvin 43:21

Another way of understanding the line: ‎ואתם הדבקים בה'‏‎ puts ‎the emphasis on Moses’ choice of the word: ‎היום‎, “this day.” The ‎Talmud in Eyruvin 22 states that as a rule, when there does ‎not seem to be any other reason for inserting this word, the ‎meaning is “that whereas you perform the commandment today, ‎your reward will be delayed until tomorrow,” i.e. some time in the ‎future. While it is a fact that the “principal” reward will be paid in ‎the hereafter, when a person performs a commandment such as ‎studying the Torah, for instance, he receives an additional and ‎almost tangible dimension of life as an immediate consequence of ‎having performed the commandment, plus an additional ‎dimension of wisdom. We know this from Job 28,28: ‎‏ הן יראת ה' היא ‏חכמה‎, “behold reverence for G’d results immediately in wisdom.” ‎This additional wisdom in turn provides an additional dimension ‎of life to those who are endowed with it. This is the meaning of ‎Moses’ telling the people that whereas their mitzvah ‎performance due to their having cleaved to Him has secured for ‎them a reward in the future, they could rest assured that there is ‎also an immediate benefit for mitzvah performance, i.e. ‎the additional dimension of one’s vitality; this latter aspect is ‎described as ‎היום אתם חיים‎, “a vitality that you experience already ‎this very day.” The word ‎אלוקיכם‎, “your G’d,” is an allusion to the ‎fact that all initiatives are indirectly traceable to the existence of ‎the Jewish people.‎