GEN1275 It is written Psalms 119:136: “My eyes have shed streams of tears for not having observed Your Torah,” and Psalms 38:19: “For I will declare my transgression; I will worry over my sin.”   One should always nurture sorrow in his heart for what has passed and worry about the future and always be afraid that he might not fulfill the requirement of repentance, as it is written Proverbs 28:14: “Happy is he who fears always.”  Even if one happens to be meritorious and completely righteous, he must always fear that he might sin in the future.  As we find in the case of Yaakov, even though the Holy One Blessed be He told him [this verse]: “And I will guard you wherever you go,” he was afraid that he might come to sin [and invalidate the assurance].   And so did King David assay Psalms 27:13: “I cannot securely believe to see the good of Hashem in the land of the living.”   TZADIK 221-3