Many have a beautiful tradition to bless their children on a Friday night.
But where does this custom come from?
(כ) וַיְבָ֨רֲכֵ֜ם בַּיּ֣וֹם הַהוּא֮ לֵאמוֹר֒ בְּךָ֗ יְבָרֵ֤ךְ יִשְׂרָאֵל֙ לֵאמֹ֔ר יְשִֽׂמְךָ֣ אֱלֹקִ֔ים כְּאֶפְרַ֖יִם וְכִמְנַשֶּׁ֑ה וַיָּ֥שֶׂם אֶת־אֶפְרַ֖יִם לִפְנֵ֥י מְנַשֶּֽׁה׃
(20) So he blessed them that day, saying, “By you shall Israel invoke blessings, saying: God make you like Ephraim and Manasseh.” Thus he put Ephraim before Manasseh.
This is Yaakov's blessing to his grandchildren, Ephraim and Manasseh. The four highlighted words form the first phrase of the Friday night blessing.
Rashi explains why...
However, Mizrachi explains that Rashi is not implying that you must bless your children, rather, if you choose to, use this language:
בך יברך הבא לברך את בניו יברכם בברכתו ויאמר איש לבנו ישימך וגו'. אמר הבא לברך שפירושו כשירצה לברך שלא תחשוב שהוא חובה לברך כל אחד מישראל את בניו לאמר ישימך וגו'
...[Rashi] says 'when he wishes to bless', the explanation being that [we are discussing] when he wants to bless, and don't think that it is an obligation for every Jew to bless their children...
The first codification of the custom to bless one's children every Friday night appears in the 17th Century Kabbalistic work 'Ma'avar Yabok'. The reason given is that Shabbos is an auspicious time for blessing, as the evil forces in the world have less power.
The bulk of the Friday night blessing consists of the priestly blessing derived from Bamidbar:
But using the priestly blessing for this purpose may not be so simple!
The Gemara records a debate regarding whether one can assume someone to be a kohen if they are acting like one.
איבעיא להו מהו להעלות מנשיאות כפים ליוחסין תיבעי למ"ד מעלין מתרומה ליוחסין ותיבעי למ"ד אין מעלין תיבעי למ"ד מעלין הני מילי תרומה דעון מיתה היא אבל נשיאות כפים דאיסור עשה לא או דלמא לא שנא תיבעי למ"ד אין מעלין הני מילי תרומה דמיתאכלא בצנעא אבל נשיאות כפים דבפרהסיא אי לאו כהן הוא כולי האי לא מחציף אינש נפשיה או דלמא לא שנא
They asked: What is the halakha regarding assuming someone's priestly status based on seeing them perform birkas kohanim? [We have seen an opinion previously that] someone who is seen eating teruma can be assumed to be a kohen [surely the same can be applied here]. No, perhaps this assumption applies only to teruma, where a non-priest who partakes of teruma performs a transgression whose punishment is death at the hand of Heaven. One would not partake of teruma and risk that punishment if he were not a priest. However, with regard to birkas kohanim, where a non-priest who recites it violates a prohibition stated as a positive mitzva, no, one cannot be certain that one would not recite the blessing if he were not a priest...
Whatever the conclusion of the Gemara's dilemma, it is clear if a non-kohen (zar) performed birkas kohanim he is transgressing a Torah command (bittul assei). Why is this a problem? Rashi explains...
The Gemara records a statement of Rabbi Yosei...
ואמר רבי יוסי מימי לא עברתי על דברי חברי יודע אני בעצמי שאיני כהן אם אומרים לי חבירי עלה לדוכן אני עולה
And Rabbi Yosei said: In all my days I never violated the words of my friends. I know about myself that I am not a priest, and nevertheless, if my friends say to me: Go up to the platform with the priests [to perform birkas kohanim], I go up.
This statement is congruent with Rashi's understanding of the previous Gemara, in which a zar ascending to perform birkas kohanim is transgressing a mitzva. If doing so is no problem, Rabbi Yosei is not proving his loyalty to his friends in any remarkable way.
However, Tosfos states...
'If my friend's say to me: Go up to the platform' - Ri does not know what prohibition there is for a non-kohen to ascend to the platform, if it isn't for [the issue of] a wasted blessing (bracha l'vatala) of the Kohanim that the Torah says 'to bless Israel'.
Tosfos implies that the actual action of a zar performing birkas kohanim does not contain any prohibition! The only issue might be that of bracha l'vatala. According to Tosfos, this was the 'extreme' activity Rabbi Yosei was willing to engage in to prove his loyalty to his friends!
To summarise, Rashi holds that it is an issur asei for a zar to perform birkas kohanim. Tosfos does not.
If this is the case, how does Tosfos read the Gemara in Kesubos which states clearly that a zar performing birkas kohanim is an issur assei?
לא ידע ר"י. פי' דא' ר"י מימי וכו' ע"ש בתו' וקשה דהא בכתובות אמרי' דזר הנוש' כפיו עובר בעשה ותי' בד"מ דבכתובות מיירי בפ"ע ובשבת מיירי עם כהנים אחרים...
Darkhei Moshe answers that in the Gemara in Kesubos it is discussing a case of a Yisrael performing Birkas Kohanim alone [and is therefore ossur]. The Gemara in Shabbos is dealing with a case with other Kohanim present [which is less of a problem]...
According to Magen Avraham (quoting Darkhei Moshe), Tosfos agrees that a Zar performing Birkas Kohanim alone is transgressing a prohibition. However, if there are Kohanim present (as there were in the case of Rabbi Yosei), there is no prohibition.
If this is the case, according to Tosfos, what is Rabbi Yosei boasting about regarding his loyalty to his friends? He isn't saying he would do anything forbidden or out of the ordinary?!
A number of answers are suggested:
1) Perhaps the issue is making a bracha l'vatala (as Tosfos mentioned).
2) Maharsha says that Rabbi Yosei would never say a bracha l'vatala for the sake of loyalty to his friends! He would just ascend with the Kohanim, a very humiliating action he would be willing to do for his friends.
Tosfos Rosh comments that this Gemara is only a parable, and of course Rabbi Yosei wouldn't break the Torah to impress his friends! He is simply employing rhetoric to make a point.
People used to have the custom of blessing their friends with the pesukim of Birkas Kohanim as they departed. Biur Halacha wonders why this isn't a problem of a zar imitating a kohen...
...וע"ז אמרה התורה אתם ולא זרים האיך מותר לזר לברך אחד לחבירו בלשון זה... ואולי יש לומר דטעם המנהג משום דס"ל כהב"ח דדוקא בפריסת ידים עובר הזר בעשה...
Based on the drasha of 'you and not non-kohanim' how is it permitted for friends to bless each other with this language?
Perhaps one can say like Bach that there is only a prohibition [of imitating kohanim] specifically if you raise your hands [like a kohein].
So this issue of friends blessing each other is cleared up, but how about blessing our children on Friday night?
We say the pesukim of birkas kohanim, with our hands raised just like a kohen!
According to Rashi, who holds that it is an issur asei to imitate kohanim in this fashion, how is this allowed?
Torah Temima - Naso #131
"A comment must be made concerning the common custom to give blessings [with birkat kohanim] through placing hands on the head of the recepient of the blessing. On what does everyone rely on to permit this? It is clear (from this source) that this blessing is restricted to kohanim and it is a prohibition based on a positive commandment for non-kohanim.
"I heard from a reliable source that the Vilna Gaon placed one hand on the head of the Gaon Rav Yechezkel Landau, the rav of Vilna, while blessing him at his wedding. They asked the Vilna Gaon about this and he replied that only kohanim in the Mikdash bless with two hands. [Thus, blessing while placing one hand does not constitute a violation.] Besides this, I have neither seen nor heard anyone address this issue."
According to Torah Temima, enlisting the support of the Vilna Gaon, it would indeed be a problem for a non-kohen to bless with two hands raised! Assuming this issue would also apply to a parent blessing their child on Friday night, they should only raise one hand whilst doing so.
However, Rav Yaakov Emden, a contemporary of the Vilna Gaon, writes in no uncertain terms that it is correct to raise two hands when blessing your children. We might suggest that whilst the Vilna Gaon holds like Rashi, thereby expressing concern about raising both hands, Rav Yaakov Emden might hold like Tosfos who has no such worries about imitating kohanim.
The 18th Century sefer 'Yosef Ometz' states that a two handed blessing is superior to a one handed blessing for kabbalistic reasons.
There are several alternative approaches to explain why blessing one's children is not an issue:
א"נ דכיון דתקנו רבנן שלא לישא כפים בלא תפלה שוב מי שאומר פסוקים אלו של ב"כ בלא תפלה בין כהן בין ישראל הוי כמכוין בפירוש שלא לקיים בזה המצוה דברכת כהנים ולכן שרי:
...alternatively, since the Rabbis instituted that you should not raise your hands when it is not during teffila, someone who says the pesukim of brikas kohanim, whether he is a kohen or yisrael, not in the context of teffila is making it clear that he is not intending to fulfil the mitzva of Birkas Kohanim and it is therefore permitted.
Pnei Yehoshua in Kesubos (25) explains that the only issue of imitating birkat kohanim would be A) in the Beit Hamikdash B) with the fully elucidated name of Hashem.
The Chazon Ish suggests that it would only be a problem if you are the presence of a kohen, as it would show disrespect to the kohen. This is a remarkable chiddush, considering it is the polar opposite of the Magen Avraham who said that it is only a problem if you are alone!
Rav Shlomo Zalman Aurbach (Shalmei Simcha 153) and Rav Ovadia Yosef (Yechaveh Da'at 5:14) both affirm that there is no problem to raise one's hands whilst blessing one's children.