Shiur Supplement #13 Daf 7a-b
A. Tosafot s.v. Be-le-va'er [7a] The gemara [last line] states that the prefix "le" refers to the FUTURE and, thus, "LE-va'er chametz" relates to the act of disposal that is to take place AFTER the berakha has been recited. Consequently, the Rashba necessitates the berakha over berit mila - LE-hakhniso bi-vrito - to be recited BEFORE the act of circumcision takes place. Rabbeinu Tam disagrees and maintains that the berakha be recited AFTER the circumcision has been performed. This is based on two related considerations:
1. The berakha over mila is NOT the typical birkhat ha-mitzva encountered in other instances where the blessing is made DIRECTLY over the individual, specific mitzva itself. Rather, one thanks and praises Hashem for having commanded us to perform mila in general. We, thus, demonstrate that the circumcision has been performed for His sake. Therefore, it is not essential for the berakha to PRECEDE the mitzva.
2. The requirement for the berakha to PRECEDE the mitzva applies only when the one performing the mitzva is the one who recites the blessing. The mohel performs the actual mila, but the father makes the berakha and thus, the requirement falls away.
It seems that #2 is based on the same logic as #1: The berakha over mila is not a DIRECT blessing over this specific, individual mitzva and, therefore, is not recited by the one performs the action (i.e., the mohel).
B. Meitivei barukh asher kideshanu... al ha-mila [lines 2-5] According to R. Pappi (see 7a) "al" implies that the mitzva has ALREADY been performed and CANNOT be recited BEFOREHAND. Thus, one must recite LE-va'er chametz and not AL bi'ur chametz. The gemara raises an objection: The prefix "le" is used when reciting the berakha BEFORE the mila. Thus, it seems that R. Pappi's assertion is incorrect.
The gemara answers that it is impossible for the mohel to "la-mul" as this implies that HE is commanded to circumcise the baby when, in fact, it is the father's obligation. Therefore "AL ha-mila" is recited instead. However, if the father performs the mila himself, he says "LA-mul.” [The following question of the gemara from the berakha over shechita and its subsequent answer are based on the same logic.]
C. Tosafot s.v. Lo - According to Tosafot, one who circumcises a convert makes the berakha "LA-mul et ha-geirim" as it is HIS obligation to perform the mila (just as it is the responsibility of the father to circumcise his own son).
D. Tosafot s.v. Be-idna - Even though one fulfills the obligation of taking the Four Species from the moment he picks up the lulav and etrog, he is still entitled to make a berakha over this mitzva as it is incumbent on him to shake the lulav during hallel. Therefore, he has not yet completed the performance of the mitzva.
E. Va-ya'avor et ha-kushi [line 27] He passed in front of the Kushi (i.e., he PRECEDED him).
F. Tosafot s.v. Al - According to Rabbeinu Tam one who is obligated to immerse in a mikva recites the berakha BEFORE immersion, with the exception of one who is in the process of conversion and is, thus, unable to make the berakha until he has immersed himself. According to the Ri, it is, nonetheless, acceptable for a menstruant woman to recite the berakha AFTER she has immersed herself as we do not wish to differentiate between the tevila of a convert and that of others.
These explanations focus on the inherent inability of the tovel (one who is immersing) to recite the berakha due to his status. However, Tosafot cite an opinion which focuses on the technicalities that prevent the berakha over tevila being recited "over la-asiyatan:" Before tevila, we do not allow one to recite the berakha as we are concerned that that he may not immerse himself due to fear of the water. He cannot recite the blessing even once he is IN the mikva as he is now naked and it is forbidden to pronounce the name of Hashem. The only viable option is for him to recite the berakha AFTER he has completed his immersion. This logic applies to ALL cases and is NOT limited to one who is converting.
According to Rashi [s.v. De-akati gavra lo chazi] one who is immersing to remove the impurity gained after a seminal emission is UNABLE to recite the berakha over tevila before immersion as he is FORBIDDEN recite ANY berakhot or learn Torah.