הלכה אויף תהילים 103:1

And already you know that the soul is sustained in the body and its activities are manifest only if the body eats. And from this understand the matter of the sacrifices, which are the hidden things of the Torah, about which it is written: ‘to My [offering by] fire, my pleasing odor’ [Nu 28:2]. The power of the higher soul increases and is added to by the fire offerings in the eating of the sacrifices, and so our rabbis said;¹¹Song of Songs Zuta, though in R. Bahya’s own paraphrased version [as per Chavel’s note]. ‘My sacrifice, My bread, to My [offering by] fire.’ It could say just ‘My bread,’ but Scripture adds, ‘to My [offering by] fire;’ to My fire you give it. This is because of the connection of the soul to its attributes. The powers of the soul are connected to the powers of the body. And understand the verse that ‘the favorite of the Strong One’ [Ps. 103:1, i.e., David] mentions: “My soul bless YHWH, all that is inside me [bless] His holy name.’ The invisible unites with the invisible, the visible with the visible. And understand this, that the powers of the soul are not visible and are actualized only through the body. If so, the body is a great necessity for the public revelation of the high degree of the soul and its perfection.

It is written: "My soul, bless Hashem and all that is within me [bless] His holy Name."¹¹Psalms 103:1. It follows that since a person needs to bless God with all his innards, he is forbidden to recite the berachah until he cleans his intestines from excrement and urine. In the morning when a person awakens he probably has a need to relieve himself or at least to urinate; therefore he should not recite the berachah over the washing of the hands at the time of washing, but rather after he relieves himself. He then washes his hands again and then recites the berachah al netilas yadayim, and then the berachah of asher yatzar, followed by the berachos on the Torah and then the berachah of Elokai neshamah.¹²According to Mishnah Berurah, the berachah of Elokai neshamah should be said after the berachah of Asher yatzar.

“Bless the Lord, O my soul; and all that is within me, bless His holy name” (Ps. 103:1). The insides of a man, even his intestines need to bless the Lord.¹Berakoth 25a. Therefore he must examine himself well when he sets to pray,²Ibid., 23a.
/3/ The Zohar, ed. Soncino, V, 326; also Shabbath 104a. because it is not fit to bless Him while bringing a belly filled with excrement before the Holy One, blessed be He. He needs to shake his entire body during prayer, as it is written, “All mine bones shall sing, Lord, Who is like unto Thee” (Ps. 35:10). It is written, “Guard thy foot when thou goest to the house of God” (Eccl. 4:17), that your feet be not soiled.⁴Berakoth 23a. And it is written “prepare to meet thy God O Israel” (Amos 4:12).⁵Ibid., 15a. When a man appears before a king of flesh and blood he does not come attired as he would for the street, he covers himself, and stands before him with awe, fear and dignity; we who go before the Lord of all the earth, blessed be His name, all the more do we need to cover ourselves and stand before Him with awe and fear.⁶Shabbath 10a. Woe to those who delay covering themselves but from Sabbath to Sabbath so that people not laugh at them.⁷They go uncovered during the week. They do not consider that perhaps they might die and be unable to give honor to Him who gave His own garment, concerning which it is written, “His raiment was as white snow” (Dan. 7:9). Concerning these people and those similar to them it is said, the wicked may prepare it but the righteous shall put it on. (Job 27:17)