My father, the Kretchnifer Rebbe shlita (quoted in Gilyon Divrei Torah Kretchnif-Yerushalaim 5779) explains by citing the explanation of his father, the Kretchnifer Rebbe zy”a on the verse (Tehillim 95:7): “Today, if you listen to My voice.” When a person has a hisorerus to serve Hashem, the yeitzer hara runs in and tries to stop him. It says, “Do you really think you are worthy of involving yourself in holy matters? Don’t you remember what you did yesterday? Do you really think you’ll be able to keep it up? Tomorrow you’ll be back to your old ways.”
The way to overcome him is to be focused on the present. Don’t worry about what you did yesterday and don’t think about tomorrow. Just worry about today and focus on serving Hashem right now. This is hinted to in the words “today if you listen to My voice.” One can listen to Hashem and serve Him properly if he is focused on “today”.
Every time that the Torah uses the word “hayom” (today), it can be considered as if it wrote the full phrase “today if you listen to My voice.” This can be seen from the Gemara (Sanhedrin 98A) where Eliyahu Hanavi told Rav Yehoshua ben Levi that he was going to come “today”, which he later explained to mean that he would come “today if you listen to My voice.”
Rav Bunim of Peshischa zy”a said that Sefer Devarim is a work of mussar and tochacha. Accordingly, this pasuk can be understood as a mussar lesson. It is saying that we can come to cling and connect to Hashem if we live “today”. If one focuses on the present day, rather than worrying about the past or the future, he can excel in Torah and mitzvos and live a life of avodas Hashem.
