Exodus 30:19 – Aaron and his sons shall wash their hands and feet from it
Responsa of the Rashba (Section 191): This verse is the source of the law mentioned in the Gemora (Brachot 15a) that one must wash before prayer
Torah Temimah Colloquial Translation on Note #32:
[Our verse above is speaking of Aaron and his sons washing their hands and feet before offering the sacrifices but it is the source of the law for washing before prayer] Because prayer [in our day] has its source [and function] equal to sacrifices [at the time of the temple] as is discussed in the Gemora Brachot 26b. However, [the use of this verse as the source for this law] is only a hook [and not a definitive proof]. We know that it is only a hook because the law of prayer is that if one does not have water available one may use pebbles or dirt or wood chip to clean one’s hands. However for the sacrifices in the temple, it was absolutely required to use water, else one may not perform the sacrifice as is stated in Gemora Zevachim 19b.
Note that the Rambam in Chapter 4 of the Laws of Prayer states that for all prayers one must wash one’s hands, but the for the morning prayers one must wash his hands and his feet. The Ravad (Abraham ben David) criticizes this statement of the Rambam and states that he does not know the source from which the Rambam stated this. Many commentaries struggle to answer this criticism of the Rambam but me (the Torah Temimah) the answer is clear. The Rambam is of the same opinion as the Rashba noted above that the source for the obligation to wash for prayer is from the obligation to wash before the sacrificial offerings in the temple. Since this is the case, we see clearly that the obligation for prayer is to wash one’s hands and one’s feet as in the verse above.
This being the case, it is clear why the Rambam distinguishes between the morning prayer and the other prayers of the day. As the Rambam states in the beginning of the Laws for Prayer, the Biblical obligation of prayer is only once a day. The other prayers of the day are rabbinic decrees. Therefore, for the other prayers of the day, we only need to be careful that we are clean. However, for the initial prayer for the day we need to fulfil the requirement of performing it as did the priests in the temple [and wash both our hands and our feet.]
Note also that that in Gemora Brachot 53a we learn in a Mishna that the verse in Leviticus 11:44 that states: “you shall make yourselves holy and be holy” [is not repetitive]. The first mention of the word “holy” refers to the washing before eating [bread] and the second mention of the word “holy” refers to the law of washing after eating [bread, and before reciting the blessing after the meal].
This reason for this statement of the Gemora is apparently not clear nor is its source clear. [I believe] that the source is almost certainly that of the second braita mentioned in Tanna d’Vei Eliyahu on our verse above.
There the beraita states, “What is the biblical source of the obligation for washing the hands? It is from the obligation of Moshe and Aaron and his sons [to wash before performing the sacrifices] For the People of Israel [in general] the source is the verse in Leviticus “make yourselves holy and be holy”. It was because of this that Rabban Gamliel would eat [all] his food in a state of purity [indicating that he had washed before eating].” [End quote of the beraita.]
In other words, just like Moshe and Aaron made themselves holy by washing before performing the sacrifices through washing, so too when it says “holy” and refers to the People of Israel it also refers to washing.
See also Tosafot in Gemora Hulin 2b where Tosafot state that it is forbidden for an unclean person to eat unclean food. There he quotes the verse “make yourselves holy and be holy” as the source for this law. This indicates that Tosafot understood this verse as a caution to the People of Israel to eat [all food] in a state of purity. The GRiV comments that he does not know the source of Tosafot’s statement and that if one looks at the Gemora Brachot 53b, one will see that the verse “make yourselves holy and be holy” is used for a different teaching.
In my opinion though, it is clear that the Tosafot were using the beraita quoted in Tanna d’Vei Eliyahu [as their source.]
Editor’s Note: In this note, the Torah Temimah shows the source of the Rambam’s opinion that there is an obligation to wash one’s hands and one’s feet before the Morning Prayer. This answers the challenge of the Ravad on the Rambam. He then shows the source to wash before and after eating bread. In doing he answers the challenge to Tosafot’s comment on Gemora Hulin 2b.