In the previous Halachot we have explained that one must have specific intentions while reciting the first verse of Keri’at Shema; if one did not, one has not fulfilled his obligation of reciting Keri’at Shema.
Let us now discuss the proper procedure for one who recited the first verse of Keri’at Shema and then realizes that he did not concentrate on the proper intentions while reciting it.
It would seem that if one read the first verse of Keri’at Shema without the proper intention, one should immediately repeat it while concentrating.
Nevertheless, the Gemara (Berachot 33b) states: “Rabbi Zera said: One who says, ‘Shema, Shema’ (i.e. the word “Shema” of the first verse of “Shema Yisrael” after which he repeats it again) should be silenced.” The reason why a person who says this is silenced is because it seems that one is accepting the yoke of Hashem along with the yoke of another deity, G-d-forbid, which is an idolatrous act. It is therefore forbidden to recite the first verse of Keri’at Shema twice, one after another.
Nonetheless, halachically speaking, the Acharonim write that if one mistakenly recited the first verse of Keri’at Shema without the proper intention, one may repeat it once again. However, it is preferable for one to pause for several seconds before reciting the verse again.
All of the above applies when reading the first verse of Keri’at Shema twice, one after another. Nevertheless, if one has already concluded the first paragraph of Keri’at Shema and only then realizes that he has not concentrated during the first verse of Keri’at Shema, one need not pause at all before repeating Keri’at Shema, for at this point, it no longer seems as if one is accepting the kingship of two deities. At this point, it is permissible to immediately repeat the first paragraph of Keri’at Shema while concentrating on the proper intentions while reciting the first verse.
