What is the source of netilat yadayim before eating bread?

Question

Where do we learn that we need to wash hands before eating bread? Why? And why bread and not other food?

Answer 1

From here:

The primary reason for requiring this washing is that in times of old (and again shortly when Mashiach arrives) before Kohanim were allowed to partake of Terumah they had to wash their hands to ensure they weren't impure. In order for them to get in the habit of doing so, the Chazal instituted this washing for all of Klal Yisroel, not just for Kohanim.

According to here, bread was the food most commonly made from Terumah grains.

Another reason given is that the Cohanim would wash their hands before performing the service in the Beis Hamikdash. Our sages say that our table is comparable to the Altar, and our bread like the offering brought on the Altar. Therefore we wash our hands before eating bread.

Does anybody have any more primary sources for these reasons? Talmud, Shulchan Aruch, etc.?

Answer 2

The Aruch haShulchan 158:1-2 brings the 2 main reasons:

1. To protect against defiling Teruma (on a rabbinical level), we are careful to wash for regular food as well.

2. Cleanliness leads a person to purity and holiness. Based on where the Torah says "v'hiskadishchem"- sanctify yourselves (Vayikra 11:44), we wash our hands and dry them prior to eating.

There is an argument as to which is the main reason. The Aruch haShulchan (158:4) says that according to Tosafos on Pesachim 115, the main reason for Netilas Yadayim is cleanliness, with the Trumah protection idea being secondary. (Based on the Tos. that we don't have a mitzva to wash on wet foods.)

Accordingly, the reason we only wash on bread is because the rabbinical mitvah of washing was only mandated where cleanliness was noticeable (Aruch haShulchan 158:3). That is by a bread which is not done with a quick bracha-eat-bracha, but is done as a meal with a long bentching. (The idea of cleanliness always applies, but without a specific mitzva.)

Answer 3

H'oulin Daf 105a

אמר רב אידי בר אבין אמר רב יצחק בר אשיין מים ראשונים מצוה ואחרונים חובה מיתיבי מים ראשונים ואחרונים חובה אמצעיים רשות מצוה לגבי רשות חובה קרי לה גופא מים ראשונים ואחרונים חובה אמצעיים רשות ראשונים נוטלין בין בכלי בין על גבי קרקע אחרונים אין נוטלין אלא בכלי ואמרי לה אין נוטלין על גבי קרקע מאי בינייהו איכא בינייהו קינסא מים ראשונים נוטלין בין בחמין בין בצונן אחרונים אין נוטלין אלא בצונן מפני שחמין מפעפעין את הידים ואין מעבירין את הזוהמא:

Soncino English Translation (page 346):

R. Idi b. Abin said in the name of R. Isaac b. Ashian: The first washing [of the hands] is a meritorious act, the last washing is a bounden duty. An objection was raised from the following: The first and last washing [of the hands] are bounden duties, the middle washing is a matter of free choice. — A meritorious act as compared with a matter of free choice can well be termed a bounden duty. [To return to] the main text: ‘The first and last washing [of the hands] are bounden duties, the middle washing is a matter of free choice’. The first washing may be performed either over a vessel or over the ground; the last washing must be performed over a vessel. Others read: The last washing may not be performed over the ground. (What is the real difference between these [two versions]? There is a difference, [where one washes over] twigs.) The first washing may be With either hot or cold water; the last washing must be with cold water only, because hot water softens the hands and does not remove the grease.

In tossefot: מים ראשונים מצוה ואחרונים חובה כו'. בברכות בסוף פרק אלו דברים (דף נג: ושם) דריש תרווייהו מקרא מוהתקדשתם אלו מים ראשונים והייתם קדושים אלו מים אחרונים

http://hebrewbooks.org/shas.aspx?mesechta=31&daf=105&format=text