Musar su Deuteronomio 30:20

And it is written in Chovath Halevavoth that it befits a man to reflect that if a book reached him [written by] a king of flesh and blood and he was in doubt as to its meaning because of the nature of the writing or its subtlety, or the profundity of the language, he would grieve greatly until he could understand it and he would set all of his heart and mind upon his understanding it. And if this is the case with a book of flesh and blood, who today is here and tomorrow in the grave, how much more so with the King of kings, the Holy One Blessed be He, who is his life and his salvation, as it is written (Devorim 30:20): "For He is your life and the length of your days."

The Torah exhorts us many times on the clinging [to G-d]: "to love the L-rd your G-d.. and to cling to Him" (Devarim 30:20), "to Him shall you cling" (Devarim 10:20, 13:5). And David said: "my soul clings to You" (Tehilim 63:9). All these verses speak of one matter, namely, the clinging with which a man clings to G-d, blessed be He, to such an extent that he is unable to part or move from Him.

One great strategy for achieving this is by clinging to the Torah, for through this one clings to the Shechinah even during one’s life. Then all the more so will one merit clinging to it after death. Thus it is related in the Zohar (Parashas Va’eschanan 268a): Rabbi Acha and Rabbi Elazar were standing together one evening after midnight engaged in study. Rabbi Elazar began a discourse: “It is written, ‘For it is your life and the length of your days that you may dwell upon the earth’ (Devarim 30:20). Come and see. The Shechinah only settles in a place where Torah is studied and in the merit of study is the world sustained. This is the meaning of the words, ‘For it is your life…that you may dwell upon the earth.’ “But if people fail to study it is said, ‘For what was the land lost? And Hashem said, ‘Because they abandoned My Torah” (Yirmeyahu 9:11-12).” Then he added: “This applies to one who is able to study and does not.” Rabbi Elazar likens this to the case of a modest and pleasant woman whose husband sets aside his conjugal duties (see Shemos 21:10) and abandons her, causing her to cry out to Heaven concerning her abandonment.