The Gemara in Masechet Berachot (28) presents a Halacha that applies to a person who is in a situation that does not allow him to properly concentrate for the recitation of the entire Amida. This might happen in a situation where one knows he will be interrupted, or if he is feeling ill. In such a case, the Gemara writes, the individual recites an abbreviated form of the Amida which is known as "Habinenu." He recites the first three and last three Berachot of the Amida in their entirety, but the middle Berachot are condensed into a single Beracha, containing a brief summary of each Beracha and ending, "Baruch Ata Hashem Shome’a Tefila." (The Gemara presents the complete text of this middle Beracha.) This abbreviated Amida thus contains seven Berachot, as opposed to the standard Amida, which consists of nineteen Berachot.
The Shulhan Aruch codifies this Halacha in Orah Haim (110), yet, interestingly enough, the vast majority of Siddurim do not include the text of "Habinenu." Even though the Shulhan Aruch rules that one recites this abbreviated prayer in situations where he is unable to properly pray the regular Amida, this prayer does not appear in conventional Siddurim, indicating that it has fallen into disuse.
Indeed, the Be’ur Halacha (essays on the Shulhan Aruch by Rav Yisrael Kagan of Radin, 1839-1933) writes that it is not customary to recite "Habinenu" because if a person cannot properly concentrate for the entire Amida, then it is likely he will not properly concentrate for a seven-Beracha prayer, either. Nowadays, people find it difficult to concentrate even for the first Beracha of the Amida, when concentration is strictly required in order for one to fulfill the obligation. We cannot assume, therefore, that a person would be able to concentrate for the recitation of "Habinenu," and there is thus no justification for reciting an abridged version of the Amida.
The Kaf Ha’haim (Rav Yaakob Haim Sofer, Baghdad-Israel, 1870-1939) notes another reason why "Habinenu" is not customarily recited even in situations where a person cannot properly concentrate for the entire Amida. There are disagreements among the Halachic authorities concerning the precise text of "Habinenu," and we therefore refrain from reciting it in order to avoid the uncertainty of whether we are reciting the proper text. For this reason, too, one should not recite "Habinenu" under any circumstances.
Therefore, even in situations where one finds it especially difficult to pray with proper concentration, he should recite the complete Amida prayer, and make an effort to concentrate at very least for the first Beracha of the Amida, and as much of the other parts of the prayer as possible.
Summary: Although the Gemara presents an abridged text of the Amida to be recited in situations where concentration is difficult, this text should not be recited nowadays. One should recite the full Amida under all circumstances, and make an effort to concentrate for as much of the prayer as possible, especially the first Beracha, during which concentration is strictly required.
