Halakhah su Isaia 63:9

The first blessing is al netilat yada’im -“over the washing of the hands”. Our rabbis z”l specifically fixed the form of this blessing with the word “netilah,” which literally means “raising high,” as the Targum translates “then a spirit lifted me up [va-tise’ni]”²Ez 3:12. – “raised me up” [va-nitaltni]. These two verbs are also used synonymously when it is written “He raised them and lifted them up [va-yitlem va-yinas’em] all the days of old.”³Is 63:9.It is necessary to raise up one’s hands when saying this blessing. Moreover this would include the point of raising hands in prayer, to concentrate one’s mind on them (i.e., the ten fingers of one’s hands) to be made holy by them from the ten sefirot. It is like someone who raises their hands upward to concentrate on opening the source above, pulling and drawing down the divine energy flow. This is what Scripture means when it says, “I reach up for your commandments which I love.”⁴Ps 119:48. This verse teaches you that in some of the commandments there is an imprint or picture above, which a person needs, in order to follow them below, so you should raise your hands toward them above. Even here over the table when you are eating, you ought to lift up your hands and raise them above.⁵Or “ought to perform the ritual of al netilat yada’im raising his hands upward …;” the Hebrew can mean either, or most likely, both. You should concentrate on the ten sefirot when you lift (or wash) before you eat, and likewise after you eat with the mayim aharonim [i.e., the washing after the meal]. Scripture talksabout this when it says, “Lift your hands toward the sanctuary and bless the Lord.”⁶Ps 134:2Similarly with the ten things that are necessary for a cup of blessing, according to the custom of those in the past.⁷R. Bahya is referring to b. Berakhot 51a:
Rabbi Zeira said in the name of Rabbi Abahu – others say it is taught in a beraita: “Ten things were said to have been required for of a cup of blessing: (1) washing and (2) rinsing it before use, (3) undiluted, (4) a full cup (5) closing it [itur] (6) covering with a cloth [ituf], (7) lifting it up with two hands and putting it in the right, and (8) elevating it at least a handbreadth from the ground, (9) looking at it; and some say, (10) sending it as a gift to household members.” Rabbi Yohanan said, “we know of only four: Washing, rinsing, undiluted, and full.”
Though R. Yohanan’s view became the accepted practice, R. Bahya is suggesting that there nevertheless was an ancient custom that did associate the rituals concerned with blessing a cup of wine with the ten sefirot. That is why Rabbi Zeira et al. specified ten, according to R. Bahya’s interpretation of his rationale. So Chavel in his notes explains R. Bahya’s reference to “the custom of those in the past.” See below, where R. Bahya discusses in more detail the ten things connected with the cup of blessing. See also the Zohar 2:157b. All this is to hint that the purpose of concentrating on our eating at the table is only for our body to be sustained and be able to serve theCreator so that our soul will merit to stand among “the ten,” and that the brilliant light be her food and hover protectively over her. And know the truth, that the structure of the body with ten fingers on the hands that can be raised above, and ten toes below, with our body in the middle – was designed this way, to get us to visualize the connection between heaven and earth. Just so, our body links our upper and lower ten digits.⁸In other words, the connection between our 10 toes and fingers with our body in the middle is analogous to the connection between our 10 fingers lifted up in netilat yada’imdown here on earth and the 10 sefirot in the upper world. This is the “imprint” of the cosmos in the human body to which R. Bahya just referred. Perhaps R. Bahya’s particular wording here to introduce this analogy, “Know the truth [ha-emet],” is an allusion to Ps. 85:11: “Truth [emet] will spring up from the ground.”