סימן ק סעיף ט
מַגְבִּיהִים אֶת יְדֵיהֶם נֶגֶד כִּתְפֵיהֶם, וּפוֹשְׁטִים אוֹתָן, וְחוֹלְקִין אֶצְבְּעוֹתֵיהֶם שֶׁיִּהְיוּ בֵינֵיהֶן חֲמִשָּׁה אֲוִירִים, דְּהַיְנוּ בֵּין שְׁתֵּי אֶצְבָּעוֹת לִשְׁתֵּי אֶצְבָּעוֹת אֲוִיר אֶחָד, וּבֵין שְׁתֵּי אֶצְבָּעוֹת לַאֲגוּדָל גַּם כֵּן אֲוִיר אֶחָד, וְכֵן בַּיָּד הַשְּׁנִיָּה, הֲרֵי אַרְבָּעָה אֲוִירִים. וּבֵין אֲגוּדָל לַאֲגוּדָל גַּם כֵּן אֲוִיר אֶחָד, הֲרֵי חֲמִשָּׁה אֲוִירִים. וְצָרִיךְ לַעֲשׂוֹת כֵּן, מִשּׁוּם דִּכְתִיב, מֵצִיץ מִן הַחֲרַכִּים, ה' חֲרַכִּים. וְצָרִיךְ לִזָּהֵר מְאֹד, שֶלֹא יִגְּעוּ רָאשֵׁי הָאֲגוּדָלִין זֶה בָּזֶה, שֶלֹּא יִתְקַלְקֵל הַחַלּוֹן. וְצָרִיךְ לְהַגְבִּיהַּ אֶת הַיָד הַיְמָנִית קְצָת לְמַעְלָה מֵהַשְׂמָאלִית, וִיהֵא אֲגוּדַל יָמִין עַל אֲגוּדַל שְׂמֹאל, (עַיֵן מָגֵן אַבְרָהָם וּלְבוּשֵׁי שְׂרָד). וּפוֹרְשִֹין כַּפֵּיהֶם, שֶׁיִּהְיֶה תּוֹךְ כַּפֵּיהֶם כְּנֶגֶד הָאָרֶץ, וְאַחוֹרֵי יְדֵיהֶם כְּנֶגֶד הַשָּׁמָיִם.
They raise their hands to the level of their shoulders30Maseches Sotah 38a. and stretch them out, and separate their fingers in such a way that there are five spaces between them. That is, between two fingers and two fingers there is one space, and between the two fingers and the thumb, there is another space, and the same with the other hand; making four spaces. And between the two thumbs there is another space, which makes a total of five spaces.31Shulchan Aruch 128:12. This must be done, because it is written, "He is peering through the lattices,"32Shir Hashirim 2:9. five open spaces.33Rosh, Maseches Megillah 3:21, Midrash. (Tanchuma Parshas Nasso) Metaphorically, Hashem watches over His people through those five spaces between the fingers of the kohanim at the duchan. (Hei Charakim, hei, is the equivalent of the number five, and Charakim means openings) He must be careful that his thumbs should not touch each other, so that there will be five spaces. He must raise his right hand slightly above the left and the right thumb should be above the left thumb. They should spread out their hands in such a way that the palms of their hands are turned toward the ground, and the back of their hands toward Heaven.34If the kohein is too weak to raise his hands properly without resting them on something, he may not duchan. This is essential to fulfilling the mitzvah. See Nodah Biyehudah Responsum 5. He should step outside until the kohanim complete the blessings. (Mishnah Berurah 128:50, Acharonim) Some say if he is tired, it is sufficient to keep the fingers separated when he says the words and may relax his fingers between words (Mishnah Berurah 128:43) and the same applies to raising the hands. (see Ksav Sofer 13, Mishnah Berurah 128:55) The kohein must stand. If he is too weak, and must lean on something, he may not duchan (Panam Meiros, Noda Biyehudah, etc.) unlike the Shvus Yaakov, who says if he is unable to stand, he may lean (or sit).
תנא דבי אליהו כל השונה הלכות בכל יום מובטח לו שהוא בן העולם הבא שנאמר הליכות עולם לו אל תקרי הליכות אלא הלכות (נדה ע"ג.)