Halakhah zu Tehillim 26:78

Yisrael 2:29 and Halikhot Shlomo 2:5).
The essential objective of netilat yadayim before Shaḥarit is cleanliness, as it is written (Tehilim 26:6): “I wash my hands clean,” and as detailed in Berakhot 15a. The reason for washing one’s hands before a meal is purification and sanctification, similar to the washing of the kohanim’s hands in the kiyor (laver) before serving in the Temple. Although there is a difference between the objectives of the two washings, the Sages instituted the morning netilat yadayim based on the model of washing before a meal, and even the berakha has the same wording. Le-khatḥila, when washing in the morning, one should take care that all the necessary requirements for washing one’s hands before a meal are met – that there is at least a revi’it of water, that she washes with a vessel, that there is human force involved in the pouring (ko’aḥ gavra), and that the appearance of the water has not changed. Be-di’avad, even if there is no revi’it of water there, or a vessel, or human force, since the water does in fact clean one for prayer, it is the opinion of SA and Rema that Al Netilat Yadayim is recited. If the appearance of the water has changed and has become unacceptable for washing before a meal, one may use it to wash her hands for Shaḥarit, but instead recite “al nekiyut yadayim” (SA 4:1, 6, 7, and 22). However, MB, 4:7, and BHL state that according to many Aḥaronim, even if the water becomes invalid for washing before a meal, one may recite Al Netilat Yadayim when washing before Shaḥarit because the water does clean her hands enough for prayer. Kaf Ha-ḥayim 4:11 and Halakha Berura 4:12 state that one does not recite a berakha on the morning netilat yadayim if there is anything that renders it invalid for washing before a meal. ]

When he arises from his bed in the morning a person is considered as a newly created being, to serve the Creator, Blessed be His Name. He, therefore, must sanctify himself and wash his hands from a vessel, [just] as a Kohein washed his hands each day from the special basin [located in the Temple] prior to his service. This washing is indicated in the Scripture as it is said: "I will wash my hands in purity and I will encircle Your altar, Hashem, to proclaim a sound of thanks, etc."¹Psalms 26:6,7. There is also another reason for this washing. When man is asleep, his holy soul departs from him, and an unclean spirit comes and dwells upon his body. When he awakens from his sleep, the unclean spirit departs from his entire body except from his fingers, from which it does not depart until he pours water upon them three times alternately.²See paragraph 3 for exact procedure. It is forbidden to walk a distance of four amohs³It is also forbidden to lie in bed without washing your hands. Within the house you may walk even more than four amohs to get water for washing. (See glossary for equivalent of amah.) without washing the hands except in cases of extreme necessity.

The hands must be washed with water until the wrist, before praying. Therefore, even though you washed your hands in the morning, if your hands touched an unclean spot i. e., parts of the body that are normally covered, where there is an accumulation of sweat, or if you scratched your head, or if you did not wash them until the wrist [in the morning], you must wash them again before praying. If there is no water available you must attempt to acquire some; even traveling four mil (72 minutes)⁹A mil is a distance of 2000 amos (cubits). This applies to one on a journey, but when not on a journey, you need not go more than a mil in searching for water. or backward one mil. If you are afraid that meanwhile the time limit for prayer will elapse, you may clean your hands on a rock or earth or with any other substance that cleans and then pray, as it is written: "I will wash my hands in purity etc."¹⁰Psalms 26:6. "I will wash," with water if possible, and if not "with nikayon,"¹¹See Maseches Berachos 15. with any substance that cleanses.