Berakhot

and he went back to the beginning. He said to him: What is the reason why your honour does this? — He replied: Because R. Shila said in the name of Rab: If one makes a mistake, he goes back to the beginning. But R. Huna has said in the name of Rab: If he goes wrong, he says, 'Blessed be He who gave [etc.]'? — He replied: Has it not been stated in reference to this that R. Menashia b. Tahalifa said in the name of Rab: This is the case only where he has not commenced, 'Who is good and bestows good'; but if he has commenced 'Who is good and bestows good', he goes back to the beginning. R. Idi b. Abin said in the name of R. Amram quoting R. Nahman who had it from Samuel: If one by mistake omitted to mention New Moon in the Tefillah, he is made to begin again; if in the grace after meals, he is not made to begin again. Said R. Idi b. Abin to R. Amram: Why this difference between Tefillah and grace? — He replied: I also had the same difficulty, and I asked R. Nahman, and he said to me: From Mar Samuel personally I have not heard anything on the subject, but let us see for ourselves. [I should say that] in the case of Tefillah, which is obligatory, he is made to begin again, but in the case of a meal, which he can eat or not eat as he pleases, he is not made to begin again. But if that is so [said the other], in the case of Sabbaths and festivals, on which it is not possible for him to abstain from eating, I should also say that if he makes a mistake he must go back to the beginning? — He replied: That is so; for R. Shila said in the name of Rab: If one goes wrong, he goes back to the beginning. But has not R. Huna said in the name of Rab that if one goes wrong he says 'Blessed is He who gave [etc.]'? — Has it not been stated in reference to this that this is the case only if he has not commenced 'Who is good and bestows good', but if he has commenced, 'Who is good and bestows good', he goes back to the beginning? HOW MUCH [MUST ONE HAVE EATEN] TO COUNT etc. This would seem to show that R. Meir's standard is an olive and R. Judah's an egg. But we understand the opposite, since we have learnt: Similarly, if one has left Jerusalem and remembers that he has in his possession holy flesh, if he has gone beyond Zofim  he burns it on the spot, and if not he goes back and burns it in front of the Temple with some of the wood piled on the altar. For what minimum quantity do they turn back? R. Meir says: In either case,  the size of an egg; R. Judah says: In either case the size of an olive.  R. Johanan said: The names must be reversed. Abaye said: There is no need to reverse. In this case [of zimmun] they differ in the interpretation of a Scriptural text. R. Meir holds that 'thou shalt eat' refers to eating and 'thou shalt be satisfied' to drinking, and the standard of eating is an olive. R. Judah holds that 'And thou shalt eat and be satisfied' signifies an eating which gives satisfaction, and this must be as much as an egg. In the other case, they differ in their reasoning. R. Meir considers that the return for a thing should be analogous to its defilement; just as its defilement is conditioned by the quantity of an egg, so is the return for it conditioned by the quantity of an egg.  R. Judah held that the return for it should be analogous to its prohibition. Just as the prohibition thereof comes into force for the quantity of an olive, so is the return for it conditioned by the quantity of an olive. MISHNAH. WHAT IS THE FORMULA FOR ZIMMUN? IF THERE ARE THREE, HE [THE ONE SAYING GRACE] SAYS, 'LET US BLESS [HIM OF WHOSE BOUNTY WE HAVE EATEN]'. IF THERE ARE THREE BESIDE HIMSELF HE SAYS, 'BLESS'. IF THERE ARE TEN, HE SAYS, LET US BLESS OUR GOD'; IF THERE ARE TEN BESIDE HIMSELF HE SAYS,'BLESS'. IT IS THE SAME WHETHER THERE ARE TEN OR TEN MYRIADS.  IF THERE ARE A HUNDRED HE SAYS, 'LET US BLESS THE LORD OUR GOD'; IF THERE ARE A HUNDRED BESIDE HIMSELF HE SAYS, 'BLESS'. IF THERE ARE A THOUSAND HE SAYS 'LET US BLESS THE LORD OUR GOD, THE GOD OF ISRAEL'; IF THERE ARE A THOUSAND BESIDE HIMSELF HE SAYS 'BLESS'. IF THERE ARE TEN THOUSAND HE SAYS, 'LET US BLESS THE LORD OUR GOD, THE GOD OF ISRAEL, THE GOD OF HOSTS, WHO DWELLS AMONG THE CHERUBIM, FOR THE FOOD WHICH WE HAVE EATEN'. IF THERE ARE TEN THOUSAND BESIDE HIMSELF HE SAYS, 'BLESS'. CORRESPONDING TO HIS INVOCATION THE OTHERS RESPOND, 'BLESSED BE THE LORD OUR GOD THE GOD OF ISRAEL, THE GOD OF HOSTS, WHO DWELLS AMONG THE CHERUBIM, FOR THE FOOD WHICH WE HAVE EATEN'. R. JOSE THE GALILEAN SAYS: THE FORMULA OF INVOCATION CORRESPONDS TO THE NUMBER ASSEMBLED, AS IT SAYS: BLESS YE GOD IN FULL ASSEMBLIES, EVEN THE LORD, YE THAT ARE FROM THE FOUNTAIN OF ISRAEL.  SAID R. AKIBA: WHAT DO WE FIND IN THE SYNAGOGUE? WHETHER THERE ARE MANY OR FEW  THE READER SAYS, 'BLESS YE THE LORD.  R. ISHMAEL SAYS: BLESS YE THE LORD WHO IS BLESSED. GEMARA. Samuel said: A man should never exclude himself from the general body.  We have learnt: IF THERE ARE THREE BESIDE HIMSELF HE SAYS 'BLESS'?  —