Musar su Salmi 103:1

And then he prospers in all his ways and in clarity of perception and the Holy One Blessed be He sends a spirit of Holiness within him and his heart rejoices and is filled with love of the Holy One, Blessed be He, and his soul is united with joy and reveals secrets and new intepretations from above, and all this because he reveres God, Blessed is He and is upright. And reason enters him. And this is what Solomon said : "My soul failed me when he spoke" (Eccl. 5:16). "Yea my body will rejoice when my lips speak right things" (Prov. 23:16). And thus said David : "Bless the Lord, O my soul" (Ps. 104:1). Because the soul which comes from above and strives upward knowing its own secret loves her Creator and eagerly assimilates His Commands, and when this soul reaches the veil (partition) and the degree which is suitable to it then she causes him (the owner) to rejoice with her hidden charms and brings him delight in her hidden chambers and at every moment his love longs for his soul and remembers it in the night as he lies upon his couch. Then God, Blessed is He, sends into her the longing for joy and the heart burns passionately from the great desire of love as it is said "I will rejoice in the Lord, my soul will be joyful in my God" (Is. 61:10). And happy is the soul that merits and experiences such joy.

But one must be especially careful about washing one’s hands before prayer, as it is written, “I will wash my hands in cleanliness, etc.” (Tehillim 26:6). And it is also written (Tehillim 103:1): “My soul shall bless Hashem and all my inwards His Holy Name” (that is, one must be sure that one’s intestines are clean as well).

And therefore David said (see Lev. Rabbah 4:8), just as the soul fills the body and carries the body and outlives the body and is unique in the body and does not eat things of the body, sees and is not seen, and is pure within the body and does not sleep, so does the Holy One, Blessed be He, fill His world, as it is said, "Do not I fill heaven and earth? saith the Lord" (Jer. 23:24). And He bears His world, as it is said, "I have made, and I will bear; Yea, I will carry and will deliver" (Is. 46:4). And He outlasts His world as it is said, "They shall perish, but thou shalt endure" (Ps. 102:27). And He is alone and unique in His world, as it is said, "Hear, O Israel, the Lord our God, the Lord is One" (Deut. 6:5). And eating does not apply to Him, as it is said, "Do I eat the flesh of bulls, or drink the blood of goats?" (Ps. 50:13). And He sees and is not seen, as it is said, "Which are the eyes of the Lord, that run to and fro through the whole earth" (Zech. 4:10). And He is pure in His world, as it is said, "Thou that art of eyes too pure to behold evil" (Hab. 1:13). And He does not sleep as it is said, "Behold, He that keepeth Israel doth neither slumber, nor sleep" (Ps. 121:4). Therefore the soul which has within it all these qualities should come and praise the Holy One, Blessed be He, Who has within Himself all these qualities.